CVE-2026-46300

Name	CVE-2026-46300
Description	In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.
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-6295-1

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	6.1.170-3	vulnerable
	bookworm (security)	6.1.172-1	vulnerable
	trixie	6.12.86-1	vulnerable
	trixie (security)	6.12.90-1	fixed
	forky, sid	7.0.9-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	trixie	6.12.90-1		DSA-6295-1
linux	source	(unstable)	7.0.9-1

Notes

https://github.com/v12-security/pocs/tree/main/fragnesia
https://lore.kernel.org/all/20260513041635.1289541-1-vakzz@zellic.io/
https://lore.kernel.org/all/agRfuVOeMI5pbHhY@v4bel/
https://git.kernel.org/linus/f84eca5817390257cef78013d0112481c503b4a3