CVE-2025-21972

Name	CVE-2025-21972
Description	In the Linux kernel, the following vulnerability has been resolved: net: mctp: unshare packets when reassembling Ensure that the frag_list used for reassembly isn't shared with other packets. This avoids incorrect reassembly when packets are cloned, and prevents a memory leak due to circular references between fragments and their skb_shared_info. The upcoming MCTP-over-USB driver uses skb_clone which can trigger the problem - other MCTP drivers don't share SKBs. A kunit test is added to reproduce the issue.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, 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
linux (PTS)	bullseye	5.10.223-1	fixed
	bullseye (security)	5.10.234-1	fixed
	bookworm	6.1.129-1	vulnerable
	bookworm (security)	6.1.128-1	vulnerable
	trixie	6.12.20-1	fixed
	sid	6.12.21-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	bullseye	(not affected)
linux	source	(unstable)	6.12.20-1

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/f5d83cf0eeb90fade4d5c4d17d24b8bee9ceeecc (6.14-rc7)