CVE-2026-20031

ClamAV CSS Image Parsing Error Handling Denial of Service Vulnerability

CVSS 5.3 MEDIUMEPSS 0.4%CWE-248

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.3EPSS 0.4%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

04 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

A vulnerability in the HTML Cascading Style Sheets (CSS) module of ClamAV could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper error handling when splitting UTF-8 strings. An attacker could exploit this vulnerability by submitting a crafted HTML file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to terminate the scanning process.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

Cisco · Cisco Secure Endpoint

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References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-css-Fn4QSZ