🛡️ CVE-2025-40327 — kernel

⚪ Unknown ✅ No Known Exploit NVD
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

perf/core: Fix system hang caused by cpu-clock usage

In the Linux kernel, the following vulnerability has been resolved:

perf/core: Fix system hang caused by cpu-clock usage

cpu-clock usage by the async-profiler tool can trigger a system hang,

which got bisected back to the following commit by Octavia Togami:

18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue

The root cause of the hang is that cpu-clock is a special type of SW

event which relies on hrtimers. The __perf_event_overflow() callback

is invoked from the hrtimer handler for cpu-clock events, and

__perf_event_overflow() tries to call cpu_clock_event_stop()

to stop the event, which calls htimer_cancel() to cancel the hrtimer.

But that's a recursion into the hrtimer code from a hrtimer handler,

which (unsurprisingly) deadlocks.

To fix this bug, use hrtimer_try_to_cancel() instead, and set

the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer()

to stop the event once it sees the PERF_HES_STOPPED flag.

[ mingo: Fixed the comments and improved the changelog. ]

Affected software

CVE-2025-40327 is recorded against 2 packages.

  • kernel (from 6.17.0 up to 6.17.8)
  • unknown

Timeline and source

Published on 9 December 2025 and last revised on 15 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2025-40327 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2025-12-09
Updated 2026-08-12
Modified 2026-07-15
Fix URL N/A

Affected Packages

Software From version Fixed in
kernel 6.17.0 6.17.8
unknown — —

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