CVE-2023-53815
Published Dec 9, 2025
Modified Apr 15, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: posix-timers: Prevent RT livelock in itimer_delete() itimer_delete() has a retry loop when the timer is concurrently expired. On non-RT kernels this just spin-waits until the timer callback has completed, except for posix CPU timers which have HAVE_POSIX_CPU_TIMERS_TASK_WORK enabled. In that case and on RT kernels the existing task could live lock when preempting the task which does the timer delivery. Replace spin_unlock() with an invocation of timer_wait_running() to handle it the same way as the other retry loops in the posix timer code.
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References
Other References
https://git.kernel.org/stable/c/0670c4c567b27bd8f999a943028f4fe60d1a1106
https://git.kernel.org/stable/c/9d9e522010eb5685d8b53e8a24320653d9d4cbbf
https://git.kernel.org/stable/c/c1968bb8a28625cc95d2ad3ca872ab98c9c36d59
https://git.kernel.org/stable/c/e7aff15ba29ba4b3052786b1636fa5c4aa39e179
https://git.kernel.org/stable/c/f1be1ed32daa053484222f7f9beb2b16c624dffd
https://git.kernel.org/stable/c/f9bd298e3e4d3fd6e19f017789a42d0f332cd555
Frequently Asked Questions
What is CVE-2023-53815? +
In the Linux kernel, the following vulnerability has been resolved:
posix-timers: Prevent RT livelock in itimer_delete()
itimer_delete() has a retry loop when the timer is concurrently expired. On
non-RT kernels this just spin-waits until the timer callback has completed,
except for posix CPU timers which have HAVE_POSIX_CPU_TIMERS_TASK_WORK
enabled.
In that case and on RT kernels the existing task could live lock when
preempting the task which does the timer delivery.
Replace spin_unlock() with an invocation of timer_wait_running() to handle
it the same way as the other retry loops in the posix timer code.
How do I check if I'm vulnerable to CVE-2023-53815? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.