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Vulnerability record · CVE-2026-43499 · published 21 May 2026

CVE-2026-43499: Linux kernel use after free vulnerability

Linux · Linux Kernel

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 ]

7.8 CVSS 3.1 High EPSS 0.28% · top 81.9% CWE-416 · Use after free
7.8CVSS 3.1 base score
0.28%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
10References
8 Sep 2026Last modified by NVD

Description

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 ]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/3bfdc63936dd4773109b7b8c280c0f3b5ae7d349 Patch
https://git.kernel.org/stable/c/3fb7394a837740770f0d6b4b30567e60786a63f2 Patch
https://git.kernel.org/stable/c/6d52dfcb2a5db86e346cf51f8fcf2071b8085166 Patch
https://git.kernel.org/stable/c/838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd
https://git.kernel.org/stable/c/88614876370aac8ad1050ad785a4c095ba17ac11 Patch
https://git.kernel.org/stable/c/8a1fc8d698ac5e5916e3082a0f74450d71f9611f Patch
https://git.kernel.org/stable/c/d8cce4773c2b23d819baf5abedc62f7b430e8745 Patch
https://git.kernel.org/stable/c/f3fa3424bceb128d2be4b3745506b22844b87db7
http://www.openwall.com/lists/oss-security/2026/07/08/12
https://cert-portal.siemens.com/productcert/html/ssa-019113.html

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Source: NIST National Vulnerability Database (record CVE-2026-43499), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.