UBUNTU-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 ]
02 / AFFECTED SOFTWARE
Affected packages
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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 ]
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/3bfdc63936dd4773109b7b8c280c0f3b5ae7d349
- https://git.kernel.org/stable/c/3bfdc63936dd4773109b7b8c280c0f3b5ae7d349
- https://git.kernel.org/stable/c/3fb7394a837740770f0d6b4b30567e60786a63f2
- https://git.kernel.org/stable/c/6d52dfcb2a5db86e346cf51f8fcf2071b8085166
- https://git.kernel.org/stable/c/88614876370aac8ad1050ad785a4c095ba17ac11
- https://git.kernel.org/stable/c/8a1fc8d698ac5e5916e3082a0f74450d71f9611f
- https://ubuntu.com/security/CVE-2026-43499
- https://ubuntu.com/security/notices/USN-8488-1
- https://ubuntu.com/security/notices/USN-8488-2
- https://ubuntu.com/security/notices/USN-8489-1
- https://ubuntu.com/security/notices/USN-8507-1
- https://ubuntu.com/security/notices/USN-8567-1
- https://ubuntu.com/security/notices/USN-8569-1
- https://ubuntu.com/security/notices/USN-8574-1
- https://ubuntu.com/security/notices/USN-8574-2
- https://ubuntu.com/security/notices/USN-8574-3
- https://ubuntu.com/security/notices/USN-8595-1
- https://ubuntu.com/security/notices/USN-8595-2
- https://ubuntu.com/security/notices/USN-8595-3
- https://ubuntu.com/security/notices/USN-8596-1
- https://ubuntu.com/security/notices/USN-8603-1
- https://ubuntu.com/security/notices/USN-8606-1
- https://ubuntu.com/security/notices/USN-8607-1
- https://ubuntu.com/security/notices/USN-8608-1
- https://ubuntu.com/security/notices/USN-8609-1
- https://ubuntu.com/security/notices/USN-8619-1
- https://ubuntu.com/security/notices/USN-8631-1
- https://ubuntu.com/security/notices/USN-8631-2
- https://ubuntu.com/security/notices/USN-8631-3
- https://ubuntu.com/security/notices/USN-8631-4
- https://ubuntu.com/security/notices/USN-8633-1
- https://ubuntu.com/security/notices/USN-8633-2
- https://ubuntu.com/security/notices/USN-8634-1
- https://ubuntu.com/security/notices/USN-8635-1
- https://ubuntu.com/security/notices/USN-8636-1
- https://ubuntu.com/security/notices/USN-8636-2
- https://ubuntu.com/security/notices/USN-8645-1
- https://www.cve.org/CVERecord?id=CVE-2026-43499