CVE-2018-0173: in the CISA KEV catalogue
Cisco IOS and IOS XE Software Improper Input Validation Vulnerability. CISA added CVE-2018-0173 to the Known Exploited Vulnerabilities catalogue on 2022-03-03 with a default due date of 2022-03-17. Known ransomware campaign use: Unknown. Forensic triage flag: No.
A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets can allow for denial-of-service (DoS). (CISA description)
- Vendor / product
- Cisco IOS and IOS XE Software
- CWE
- CWE-20
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 7.6%, percentile 94 (scored 2026-11-03)
EPSS puts about 7.6 in 100 odds (7.6%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 94% 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.
Frequently asked questions
Is CVE-2018-0173 in the CISA KEV catalogue?
Yes. CISA added CVE-2018-0173 (Cisco IOS and IOS XE Software Improper Input Validation Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-03-03. CISA's default due date for it is 2022-03-17.
Is CVE-2018-0173 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2018-0173. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2018-0173?
CISA's required action: Apply updates per vendor instructions.
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-2018-0173