CVE-2026-20031

Name	CVE-2026-20031
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-4852-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
clamav (PTS)	bookworm	1.4.3+dfsg-1~deb12u2	vulnerable
	bookworm (security)	1.4.6+dfsg-0+deb12u1	fixed
	trixie	1.4.3+dfsg-1	vulnerable
	forky, sid	1.4.6+dfsg-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Origin
clamav	source	bookworm	1.4.6+dfsg-0+deb12u1	DLA-4852-1
clamav	source	trixie	1.4.6+dfsg-1~deb13u1
clamav	source	(unstable)	1.4.4+dfsg-1

Notes

[bullseye] - clamav <postponed> (Minor issue; backport with stable release updates)
https://blog.clamav.net/2026/03/clamav-152-and-144-security-patch.html