CVE-2026-23436

Name	CVE-2026-23436
Description	In the Linux kernel, the following vulnerability has been resolved: net: shaper: protect from late creation of hierarchy We look up a netdev during prep of Netlink ops (pre- callbacks) and take a ref to it. Then later in the body of the callback we take its lock or RCU which are the actual protections. The netdev may get unregistered in between the time we take the ref and the time we lock it. We may allocate the hierarchy after flush has already run, which would lead to a leak. Take the instance lock in pre- already, this saves us from the race and removes the need for dedicated lock/unlock callbacks completely. After all, if there's any chance of write happening concurrently with the flush - we're back to leaking the hierarchy. We may take the lock for devices which don't support shapers but we're only dealing with SET operations here, not taking the lock would be optimizing for an error case.
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
linux (PTS)	bullseye	5.10.223-1	fixed
	bullseye (security)	5.10.251-1	fixed
	bookworm	6.1.159-1	fixed
	bookworm (security)	6.1.164-1	fixed
	trixie	6.12.73-1	fixed
	trixie (security)	6.12.74-2	fixed
	forky	6.19.11-1	fixed
	sid	6.19.13-1	fixed

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

Package	Type	Release	Fixed Version
linux	source	bullseye	(not affected)
linux	source	bookworm	(not affected)
linux	source	trixie	(not affected)
linux	source	(unstable)	6.19.10-1

Notes

[trixie] - linux <not-affected> (Vulnerable code not present)
[bookworm] - linux <not-affected> (Vulnerable code not present)
[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/d75ec7e8ba1979a1eb0b9211d94d749cdce849c8 (7.0-rc5)