CVSS 3.1 Calculator
The CVSS 3.1 calculator turns Base, Temporal and Environmental metric values into a score from 0.0 to 10.0, a severity rating and a CVSS:3.1 vector string. The Base score comes from two sub-scores: Impact, built from the Confidentiality, Integrity and Availability metrics (ISS), and Exploitability, which is 8.22 × Attack Vector × Attack Complexity × Privileges Required × User Interaction. The sum is rounded up to one decimal place.
Temporal metrics multiply the Base score by Exploit Code Maturity, Remediation Level and Report Confidence. Environmental metrics re-score the vulnerability for your environment with Security Requirements and Modified Base metrics. Open "How this score was computed" below the result to see every intermediate value.
CVSS v3.1 score 9.8, Critical, CVSS-B
- Base
- 9.8
Load a worked example
The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and…
Specialized access conditions or extenuating circumstances do not exist.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out…
The vulnerable system can be exploited without interaction from any user.
An exploited vulnerability can only affect resources managed by the same security authority.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker.
There is a total loss of integrity, or a complete loss of protection.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score,…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score,…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score,…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental…
Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental…
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
Not Defined: the corresponding Base metric value is used (this is the default).
How this score was computed
Result
- Score to publish
9.8 (CVSS-B)Base score.
Base score
- Impact Sub-Score (ISS)
1 − [(1 − C) × (1 − I) × (1 − A)]1 − [(1 − 0.56) × (1 − 0.56) × (1 − 0.56)] = 0.9148 - Impact (Scope Unchanged)
6.42 × ISS6.42 × 0.9148 = 5.8731 - Exploitability
8.22 × AV × AC × PR × UI8.22 × 0.85 × 0.77 × 0.85 × 0.85 = 3.887 - Base score
Roundup(Minimum[Impact + Exploitability, 10])Roundup(min(9.7602, 10)) = Roundup(9.7602) = 9.8
Scoring runs in your browser; nothing you enter is uploaded. Independent implementation of the FIRST.org CVSS v3.1 specification; CVSS is owned by FIRST.org, Inc. Severity scale: None 0.0, Low 0.1–3.9, Medium 4.0–6.9, High 7.0–8.9, Critical 9.0–10.0.
TL;DRWhat this calculator does
5 points
- Base = Roundup(min(Impact + Exploitability, 10)); with Scope Changed, Roundup(min(1.08 × (Impact + Exploitability), 10)); 0 if Impact ≤ 0.
- Roundup is the smallest one-decimal number that is equal to or higher than its input, computed with the integer method from Appendix A of the specification.
- The Environmental Modified Impact for a changed scope differs from v3.0: 7.52 × (MISS − 0.029) − 3.25 × (MISS × 0.9731 − 0.02)^13.
- Severity scale: None 0.0, Low 0.1 to 3.9, Medium 4.0 to 6.9, High 7.0 to 8.9 and Critical 9.0 to 10.0.
- A v3.1 vector may list metrics in any order; omitted Temporal and Environmental metrics are Not Defined.
CVSS 3.1 equations
From section 7 of the CVSS v3.1 Specification Document:
ISS = 1 − [(1 − Confidentiality) × (1 − Integrity) × (1 − Availability)]Impact = 6.42 × ISS (Scope Unchanged); 7.52 × (ISS − 0.029) − 3.25 × (ISS − 0.02)^15 (Scope Changed)Exploitability = 8.22 × AttackVector × AttackComplexity × PrivilegesRequired × UserInteractionBaseScore = 0 if Impact ≤ 0; otherwise Roundup(min(Impact + Exploitability, 10)), or Roundup(min(1.08 × (Impact + Exploitability), 10)) if Scope is ChangedTemporalScore = Roundup(BaseScore × ExploitCodeMaturity × RemediationLevel × ReportConfidence)MISS = min(1 − [(1 − CR × MC) × (1 − IR × MI) × (1 − AR × MA)], 0.915)ModifiedImpact = 6.42 × MISS (Modified Scope Unchanged); 7.52 × (MISS − 0.029) − 3.25 × (MISS × 0.9731 − 0.02)^13 (Changed)ModifiedExploitability = 8.22 × MAV × MAC × MPR × MUIEnvironmentalScore = 0 if ModifiedImpact ≤ 0; otherwise Roundup(Roundup(min([1.08 ×] (ModifiedImpact + ModifiedExploitability), 10)) × E × RL × RC)Roundup returns the smallest number, specified to one decimal place, that is equal to or higher than its input. Appendix A of the specification suggests multiplying by 100,000, rounding to an integer and rounding up with integer arithmetic so floating-point error cannot change the result; this calculator does that. The Modified Impact formula above (exponent 13, MISS × 0.9731) differs from v3.0.
Weights used (Table 16 of the specification):
| Metric | Weights |
|---|---|
| Attack Vector (AV) | Network 0.85, Adjacent 0.62, Local 0.55, Physical 0.2 |
| Attack Complexity (AC) | Low 0.77, High 0.44 |
| Privileges Required (PR) | None 0.85; Low 0.62 (0.68 if Scope is Changed); High 0.27 (0.5 if Scope is Changed) |
| User Interaction (UI) | None 0.85, Required 0.62 |
| Confidentiality / Integrity / Availability | High 0.56, Low 0.22, None 0 |
| Exploit Code Maturity (E) | Not Defined 1, High 1, Functional 0.97, Proof-of-Concept 0.94, Unproven 0.91 |
| Remediation Level (RL) | Not Defined 1, Unavailable 1, Workaround 0.97, Temporary Fix 0.96, Official Fix 0.95 |
| Report Confidence (RC) | Not Defined 1, Confirmed 1, Reasonable 0.96, Unknown 0.92 |
| Security Requirements (CR, IR, AR) | Not Defined 1, High 1.5, Medium 1, Low 0.5 |
CVSS 3.1 metrics explained
Descriptions are excerpted from the CVSS v3.1 Specification Document. Each metric has a vector abbreviation (in brackets) that appears in the vector string.
Base metrics · 8 metrics
Intrinsic qualities of the vulnerability that stay constant over time and across environments. Usually set by the vendor or advisory.
Attack Vector (AV)
This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the Base Score) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable component.
- Network (AV:N) — The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
- Adjacent (AV:A) — The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
- Local (AV:L) — The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
- Physical (AV:P) — The attack requires the attacker to physically touch or manipulate the vulnerable component. Physical interaction may be brief (e.g., evil maid attack) or persistent. An example of such an attack is a cold boot attack in which an attacker gains access to disk encryption keys after physically accessing the target system. Other examples include peripheral attacks via FireWire/USB Direct Memory Access (DMA).
Attack Complexity (AC)
This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. As described below, such conditions may require the collection of more information about the target, or computational exceptions.
- Low (AC:L) — Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
- High (AC:H) — A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.2 For example, a successful attack may depend on an attacker overcoming any of the following conditions:The attacker must gather knowledge about the environment in which the vulnerable target/component exists.
Privileges Required (PR)
This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The Base Score is greatest if no privileges are required.
- None (PR:N) — The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
- Low (PR:L) — The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
- High (PR:H) — The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable component allowing access to component-wide settings and files.
User Interaction (UI)
This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
- None (UI:N) — The vulnerable system can be exploited without interaction from any user.
- Required (UI:R) — Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.
Scope (S)
The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources…
- Unchanged (S:U) — An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
- Changed (S:C) — An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality (C)
This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
- High (C:H) — There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
- Low (C:L) — There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
- None (C:N) — There is no loss of confidentiality within the impacted component.
Integrity (I)
This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. The Base Score is greatest when the consequence to the impacted component is highest.
- High (I:H) — There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
- Low (I:L) — Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
- None (I:N) — There is no loss of integrity within the impacted component.
Availability (A)
This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the impacted component, this metric refers to the loss of availability of the impacted component itself, such as a networked service…
- High (A:H) — There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed).
- Low (A:L) — Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.
- None (A:N) — There is no impact to availability within the impacted component.
Temporal metrics · 3 metrics
Characteristics that change over time, such as exploit code and available fixes. Optional.
Exploit Code Maturity (E)
This metric measures the likelihood of the vulnerability being attacked, and is typically based on the current state of exploit techniques, exploit code availability, or active, “in-the-wild” exploitation. Public availability of easy-to-use exploit code increases the number of potential attackers by including those who are unskilled, thereby increasing the severity of the vulnerability.
- Not Defined (E:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score, i.e., it has the same effect on scoring as assigning High.
- High (E:H) — Functional autonomous code exists, or no exploit is required (manual trigger) and details are widely available. Exploit code works in every situation, or is actively being delivered via an autonomous agent (such as a worm or virus). Network-connected systems are likely to encounter scanning or exploitation attempts. Exploit development has reached the level of reliable, widely available, easy-to-use automated tools.
- Functional (E:F) — Functional exploit code is available. The code works in most situations where the vulnerability exists.
- Proof-of-Concept (E:P) — Proof-of-concept exploit code is available, or an attack demonstration is not practical for most systems. The code or technique is not functional in all situations and may require substantial modification by a skilled attacker.
- Unproven (E:U) — No exploit code is available, or an exploit is theoretical.
Remediation Level (RL)
The Remediation Level of a vulnerability is an important factor for prioritization. The typical vulnerability is unpatched when initially published. Workarounds or hotfixes may offer interim remediation until an official patch or upgrade is issued.
- Not Defined (RL:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score, i.e., it has the same effect on scoring as assigning Unavailable.
- Unavailable (RL:U) — There is either no solution available or it is impossible to apply.
- Workaround (RL:W) — There is an unofficial, non-vendor solution available. In some cases, users of the affected technology will create a patch of their own or provide steps to work around or otherwise mitigate the vulnerability.
- Temporary Fix (RL:T) — There is an official but temporary fix available. This includes instances where the vendor issues a temporary hotfix, tool, or workaround.
- Official Fix (RL:O) — A complete vendor solution is available. Either the vendor has issued an official patch, or an upgrade is available.
Report Confidence (RC)
This metric measures the degree of confidence in the existence of the vulnerability and the credibility of the known technical details. Sometimes only the existence of vulnerabilities is publicized, but without specific details. For example, an impact may be recognized as undesirable, but the root cause may not be known.
- Not Defined (RC:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Temporal Score, i.e., it has the same effect on scoring as assigning Confirmed.
- Confirmed (RC:C) — Detailed reports exist, or functional reproduction is possible (functional exploits may provide this). Source code is available to independently verify the assertions of the research, or the author or vendor of the affected code has confirmed the presence of the vulnerability.
- Reasonable (RC:R) — Significant details are published, but researchers either do not have full confidence in the root cause, or do not have access to source code to fully confirm all of the interactions that may lead to the result. Reasonable confidence exists, however, that the bug is reproducible and at least one impact is able to be verified (proof-of-concept exploits may provide this).
- Unknown (RC:U) — There are reports of impacts that indicate a vulnerability is present. The reports indicate that the cause of the vulnerability is unknown, or reports may differ on the cause or impacts of the vulnerability. Reporters are uncertain of the true nature of the vulnerability, and there is little confidence in the validity of the reports or whether a static Base Score can be applied given the differences described.
Environmental metrics · 11 metrics
Characteristics unique to your environment: how much each of confidentiality, integrity and availability matters, and Base values you override. Set by the organisation that deploys the product. Optional.
Confidentiality Requirement (CR)
These metrics enable the consumer to customize the score depending on the importance of the affected IT asset to the analyst’s organization, measured in terms of confidentiality, integrity, and availability.
- Not Defined (CR:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental Score, i.e., it has the same effect on scoring as assigning Medium.
- High (CR:H) — Loss of confidentiality is likely to have a catastrophic adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Medium (CR:M) — Loss of confidentiality is likely to have a serious adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Low (CR:L) — Loss of confidentiality is likely to have only a limited adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
Integrity Requirement (IR)
These metrics enable the consumer to customize the score depending on the importance of the affected IT asset to the analyst’s organization, measured in terms of confidentiality, integrity, and availability.
- Not Defined (IR:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental Score, i.e., it has the same effect on scoring as assigning Medium.
- High (IR:H) — Loss of integrity is likely to have a catastrophic adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Medium (IR:M) — Loss of integrity is likely to have a serious adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Low (IR:L) — Loss of integrity is likely to have only a limited adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
Availability Requirement (AR)
These metrics enable the consumer to customize the score depending on the importance of the affected IT asset to the analyst’s organization, measured in terms of confidentiality, integrity, and availability.
- Not Defined (AR:X) — Assigning this value indicates there is insufficient information to choose one of the other values, and has no impact on the overall Environmental Score, i.e., it has the same effect on scoring as assigning Medium.
- High (AR:H) — Loss of availability is likely to have a catastrophic adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Medium (AR:M) — Loss of availability is likely to have a serious adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
- Low (AR:L) — Loss of availability is likely to have only a limited adverse effect on the organization or individuals associated with the organization (e.g., employees, customers).
Modified Attack Vector (MAV)
Modified version of the Base metric "Attack Vector". It lets you override the Base value for your own environment. This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the Base Score) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable component.
- Not Defined (MAV:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- Network (MAV:N) — The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
- Adjacent (MAV:A) — The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
- Local (MAV:L) — The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
- Physical (MAV:P) — The attack requires the attacker to physically touch or manipulate the vulnerable component. Physical interaction may be brief (e.g., evil maid attack) or persistent. An example of such an attack is a cold boot attack in which an attacker gains access to disk encryption keys after physically accessing the target system. Other examples include peripheral attacks via FireWire/USB Direct Memory Access (DMA).
Modified Attack Complexity (MAC)
Modified version of the Base metric "Attack Complexity". It lets you override the Base value for your own environment. This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. As described below, such conditions may require the collection of more information about the target, or computational exceptions.
- Not Defined (MAC:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- Low (MAC:L) — Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
- High (MAC:H) — A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.2 For example, a successful attack may depend on an attacker overcoming any of the following conditions:The attacker must gather knowledge about the environment in which the vulnerable target/component exists.
Modified Privileges Required (MPR)
Modified version of the Base metric "Privileges Required". It lets you override the Base value for your own environment. This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The Base Score is greatest if no privileges are required.
- Not Defined (MPR:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- None (MPR:N) — The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
- Low (MPR:L) — The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
- High (MPR:H) — The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable component allowing access to component-wide settings and files.
Modified User Interaction (MUI)
Modified version of the Base metric "User Interaction". It lets you override the Base value for your own environment. This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
- Not Defined (MUI:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- None (MUI:N) — The vulnerable system can be exploited without interaction from any user.
- Required (MUI:R) — Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.
Modified Scope (MS)
Modified version of the Base metric "Scope". It lets you override the Base value for your own environment. The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources…
- Not Defined (MS:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- Unchanged (MS:U) — An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
- Changed (MS:C) — An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Modified Confidentiality (MC)
Modified version of the Base metric "Confidentiality". It lets you override the Base value for your own environment. This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
- Not Defined (MC:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- High (MC:H) — There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
- Low (MC:L) — There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
- None (MC:N) — There is no loss of confidentiality within the impacted component.
Modified Integrity (MI)
Modified version of the Base metric "Integrity". It lets you override the Base value for your own environment. This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. The Base Score is greatest when the consequence to the impacted component is highest.
- Not Defined (MI:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- High (MI:H) — There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
- Low (MI:L) — Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
- None (MI:N) — There is no loss of integrity within the impacted component.
Modified Availability (MA)
Modified version of the Base metric "Availability". It lets you override the Base value for your own environment. This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the impacted component, this metric refers to the loss of availability of the impacted component itself, such as a networked service…
- Not Defined (MA:X) — Not Defined: the corresponding Base metric value is used (this is the default).
- High (MA:H) — There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed).
- Low (MA:L) — Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.
- None (MA:N) — There is no impact to availability within the impacted component.
CVSS 3.1 severity ratings
The qualitative severity rating scale in the CVSS 3.1 specification (use is optional):
| Rating | CVSS score |
|---|---|
| None | 0.0 |
| Low | 0.1 – 3.9 |
| Medium | 4.0 – 6.9 |
| High | 7.0 – 8.9 |
| Critical | 9.0 – 10.0 |
Worked CVSS 3.1 examples
Use “Load a worked example” in the calculator to open any of these. Scores are computed live by the same engine.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HThe classic Critical profile: network, no privileges, no user interaction, High C/I/A.
Source: FIRST CVSS v3.1 User Guide examples / v4.0 Examples page.
Open in the calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HImpact crosses a security boundary (Scope Changed), which raises the Base score to the 10.0 maximum.
Source: FIRST CVSS v3.1 User Guide examples / v4.0 Examples page.
Open in the calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NA victim must click (User Interaction Required) and the scope changes into the browser.
Source: FIRST CVSS v3.1 User Guide examples / v4.0 Examples page.
Open in the calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:F/RL:O/RC:CFunctional exploit code, an official fix and a confirmed report lower the Base 7.5 to 7.0.
Source: FIRST CVSS v3.1 User Guide examples / v4.0 Examples page.
Open in the calculatorFrequently asked questions
What is the CVSS 3.1 calculator and how is the score computed?
It scores a vulnerability with the CVSS v3.1 equations. ISS = 1 − [(1 − C) × (1 − I) × (1 − A)]; Impact is 6.42 × ISS when Scope is Unchanged, or 7.52 × (ISS − 0.029) − 3.25 × (ISS − 0.02)^15 when Scope is Changed; Exploitability is 8.22 × AV × AC × PR × UI. The Base score is 0 if Impact is 0 or less, otherwise Roundup(min(Impact + Exploitability, 10)), with a 1.08 multiplier on the sum when Scope is Changed.
How is a CVSS 3.1 score rounded?
With Roundup, which returns the smallest number, specified to one decimal place, that is equal to or higher than its input: Roundup(4.02) is 4.1 and Roundup(4.00) is 4.0. Appendix A of the specification recommends multiplying the input by 100,000, converting to the nearest integer and rounding up with integer arithmetic so that floating-point error cannot push a value such as 0.30000000000000004 up to 0.4. This calculator uses that method.
What is the difference between Base, Temporal and Environmental scores?
The Base score reflects intrinsic characteristics that stay constant over time and across environments and is usually produced by the vendor or advisory. The Temporal score adjusts it for factors that change over time, such as exploit code availability and fixes. The Environmental score adjusts for the organisation's own environment, including the importance of the asset and mitigations in place. Temporal and Environmental metrics are optional.
What does Scope mean in CVSS 3.1?
Scope records whether a vulnerability in one component impacts resources beyond its security scope, meaning a different security authority. Unchanged means the impact stays with the same authority; Changed means it crosses a trust boundary. Scope Changed raises the Base score, and it also changes the Privileges Required weights for Low (0.68 instead of 0.62) and High (0.5 instead of 0.27).
How is CVSS 3.1 different from CVSS 3.0?
The metrics are the same. The v3.1 specification changes the exponent in the Modified Impact formula (used for the Environmental score when Modified Scope is Changed) to 13 with a MISS × 0.9731 factor, where v3.0 used exponent 15, and it adds Appendix A, which defines Roundup with integer arithmetic. Base and Temporal scores are computed the same way.
How do I read a CVSS 3.1 vector string?
It begins with CVSS:3.1 and lists metric:value pairs separated by slashes, for example CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. AV:N means Attack Vector Network and C:H means Confidentiality High. All eight Base metrics are required; Temporal and Environmental metrics may be omitted and are then Not Defined; a metric must not appear twice; programs must accept any metric order.
Sources and official calculators
Official calculators: FIRST CVSS v3.1 calculator · NVD CVSS v3 calculator
CVSS is a trademark of FIRST.org, Inc. This calculator is an independent implementation of the published specifications and is not affiliated with FIRST or NIST. Specification text and examples were read on 3 November 2026.