CVE-2026-33526

Name	CVE-2026-33526
Description	Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. Version 7.5 contains a patch.
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)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
squid (PTS)	bullseye	4.13-10+deb11u3	vulnerable
	bullseye (security)	4.13-10+deb11u6	vulnerable
	bookworm	5.7-2+deb12u5	vulnerable
	bookworm (security)	5.7-2+deb12u4	vulnerable
	trixie, trixie (security)	6.13-2+deb13u1	vulnerable
	forky, sid	7.5-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
squid	source	(unstable)	7.5-1

Notes

[trixie] - squid <no-dsa> (Minor issue)
[bookworm] - squid <no-dsa> (Minor issue)
[bullseye] - squid <postponed> (Minor issue)
https://www.openwall.com/lists/oss-security/2026/03/25/2
Fixed by: https://github.com/squid-cache/squid/commit/8a7d42f9d44befb8fcbbb619505587c8de6a1e91 (SQUID_7_5)