Use After Free in Linux

CVE-2026-43499

In the Linux kernel, the following vulnerability has been resolved: rtmutex: Use waiter::task instead of current in remove_waiter() remove_waiter() is used by the slowlock paths, but it is also used for proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from futex_requeue(). In the latter case waiter::task is not current, but remove_waiter() operates on current for the dequeue operation. That results in several problems: 1) the rbtree dequeue happens without waiter::task::pi_lock being held 2) the waiter task's pi_blocked_on state is not cleared, which leaves a dangling pointer primed for UAF around. 3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter task Use waiter::task instead of current in all related operations in remove_waiter() to cure those problems. [ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the changelog ]

Vulnerability class: Use-After-Free

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (18.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-43499: held from 0.008 to 0.003.

EPSS over last 30 days · oldest: 0.008 · newest: 0.003 · change: -0.005

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-43499?
CVE-2026-43499 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2026-05-21.
How severe is CVE-2026-43499?
High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2026-43499 known to be exploited?
182 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.