CVE-2026-91768

Name	CVE-2026-91768
Description	The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.
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	DSA-6514-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
php8.2 (PTS)	bookworm	8.2.32-1~deb12u1	vulnerable
	bookworm (security)	8.2.33-1~deb12u1	vulnerable
php8.4 (PTS)	trixie	8.4.24-1~deb13u1	vulnerable
	trixie (security)	8.4.26-1~deb13u1	fixed
	forky, sid	8.4.24-1	vulnerable

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

Package	Type	Release	Fixed Version	Origin
php8.2	source	(unstable)	(unfixed)
php8.4	source	trixie	8.4.26-1~deb13u1	DSA-6514-1
php8.4	source	(unstable)	(unfixed)

https://github.com/php/php-src/security/advisories/GHSA-62xp-839h-2637
https://github.com/php/php-src/blob/php-8.4.26/NEWS