CVE-2026-53166

Name	CVE-2026-53166
Description	In the Linux kernel, the following vulnerability has been resolved: futex/requeue: Prevent NULL pointer dereference in remove_waiter() on self-deadlock When FUTEX_CMP_REQUEUE_PI requeues a non-top waiter that already owns the target PI futex, task_blocks_on_rt_mutex() returns -EDEADLK before setting waiter->task. The subsequent remove_waiter() in rt_mutex_start_proxy_lock() dereferences the NULL waiter->task, causing a kernel crash. Add a self-deadlock check for non-top waiters before calling rt_mutex_start_proxy_lock(), analogous to the top-waiter check in futex_lock_pi_atomic().
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)	5.10.259-1	fixed
	bookworm	6.1.170-3	vulnerable
	bookworm (security)	6.1.176-1	vulnerable
	trixie	6.12.86-1	vulnerable
	trixie (security)	6.12.95-1	vulnerable
	forky	7.0.13-1	fixed
	sid	7.1.3-1	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)	7.0.13-1

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/74e144274af39935b0f410c0ee4d2b91c3730414 (7.1-rc7)