CVE-2023-20273: in the CISA KEV catalogue

Cisco IOS XE Web UI Command Injection Vulnerability. CISA added CVE-2023-20273 to the Known Exploited Vulnerabilities catalogue on 2023-10-23 with a default due date of 2023-10-27. Known ransomware campaign use: Unknown. Forensic triage flag: No.

Cisco IOS XE contains a command injection vulnerability in the web user interface. When chained with CVE-2023-20198, the attacker can leverage the new local user to elevate privilege to root and write the implant to the file system. Cisco identified CVE-2023-20273 as the vulnerability exploited to deploy the implant. CVE-2021-1435, previously associated with the exploitation events, is no longer believed to be related to this activity. (CISA description)

Vendor / product: Cisco Cisco IOS XE Web UI
CWE: CWE-78
CISA required action: Verify that instances of Cisco IOS XE Web UI are in compliance with BOD 23-02 and apply mitigations per vendor instructions. For affected products (Cisco IOS XE Web UI exposed to the internet or to untrusted networks), follow vendor instructions to determine if a system may have been compromised and immediately report positive findings to CISA.
EPSS: 93%, percentile 99 (scored 2026-11-03)

EPSS puts about 93 in 100 odds (93%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.

Vendor and reference links (from CISA)

Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.

Data dates. CISA KEV catalogue version 2026.11.03, released 2026-11-03, 1,767 entries (checked 2026-11-03). EPSS model v2026.06.15, scored 2026-11-03, 399,388 CVEs. Sources: CISA and FIRST (EPSS by FIRST; scores generated by Empirical Security). Copied to our own database and refreshed automatically; if a refresh fails, the previous copy keeps serving with its own date.

Frequently asked questions

Is CVE-2023-20273 in the CISA KEV catalogue?

Yes. CISA added CVE-2023-20273 (Cisco IOS XE Web UI Command Injection Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-10-23. CISA's default due date for it is 2023-10-27.

Is CVE-2023-20273 used in ransomware attacks?

CISA marks known ransomware campaign use as Unknown for CVE-2023-20273. That means CISA lacks confirmation, not that ransomware groups do not use it.

What should I do about CVE-2023-20273?

CISA's required action: Verify that instances of Cisco IOS XE Web UI are in compliance with BOD 23-02 and apply mitigations per vendor instructions. For affected products (Cisco IOS XE Web UI exposed to the internet or to untrusted networks), follow vendor instructions to determine if a system may have been compromised and immediately report positive findings to CISA.

Sources

CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
NVD record for CVE-2023-20273