System hang via recursive hrtimer cancellation
Published Dec 9, 2025 · Updated May 23, 2026
Deadlock in Linux 6.16.8 through 6.17.7 allows local users to hang the system by running cpu-clock profiling workloads. In kernel/events/core.c, __perf_event_overflow() calls cpu_clock_event_stop(), which invokes hrtimer_cancel() recursively from the active hrtimer handler and deadlocks. Triggering requires local perf-event execution permitted by the system's perf access controls; the reported consequence is a system-wide hang, not data access or code execution.
Summary
What happened
Deadlock in Linux 6.16.8 through 6.17.7 allows local users to hang the system by running cpu-clock profiling workloads. In kernel/events/core.c, __perf_event_overflow() calls cpu_clock_event_stop(), which invokes hrtimer_cancel() recursively from the active hrtimer handler and deadlocks. Triggering requires local perf-event execution permitted by the system's perf access controls; the reported consequence is a system-wide hang, not data access or code execution.
The record
- CVE
- CVE-2025-40327
- Published
- Dec 9, 2025
- Updated
- May 23, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Dec 9, 2025CVE publishedPublication date reported by the CVE source.
- May 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=18dbcbfabfffc4a5d3ea10290c5ad27f22b0d240 <6b8c512811644cf2f5eaf6f44e928683c54127f0
- Affected versionversion=18dbcbfabfffc4a5d3ea10290c5ad27f22b0d240 <eb3182ef0405ff2f6668fd3e5ff9883f60ce8801
- Affected versionversion=6.16.8 <6.17
- Affected versionversion=6.17
- Affected versionversion=b2de0c9ce8e542b5cb4cd3944620d9dd1ea1f0ac
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What is affected?
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Attacks
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Technologies
Your stack
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