CVE-2026-31664

Name	CVE-2026-31664
Description	In the Linux kernel, the following vulnerability has been resolved: xfrm: clear trailing padding in build_polexpire() build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire().
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-4561-1, DSA-6238-1, DSA-6243-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bullseye	5.10.223-1	vulnerable
	bullseye (security)	5.10.251-5	vulnerable
	bookworm	6.1.159-1	vulnerable
	bookworm (security)	6.1.172-1	fixed
	trixie	6.12.73-1	vulnerable
	trixie (security)	6.12.88-1	fixed
	forky	7.0.4-1	fixed
	sid	7.0.7-1	fixed
linux-6.1 (PTS)	bullseye (security)	6.1.170-3~deb11u1	fixed

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

Package	Type	Release	Fixed Version	Origin
linux	source	bookworm	6.1.170-1	DSA-6243-1
linux	source	trixie	6.12.85-1	DSA-6238-1
linux	source	(unstable)	6.19.13-1
linux-6.1	source	bullseye	6.1.170-1~deb11u1	DLA-4561-1

https://git.kernel.org/linus/71a98248c63c535eaa4d4c22f099b68d902006d0 (7.0)