Local privilege escalation via CPU-timer race
Published Jul 22, 2025 · Updated Sep 8, 2026
A race condition in Linux POSIX CPU timers allows local users to gain kernel privileges or crash the system through local syscalls. After an exiting non-autoreaping task passes exit_notify(), concurrent reaping and timer deletion can evade the firing-state check and leave a freed sigqueue linked for later kernel access. Exploitation requires local code execution and a kernel without CONFIG_POSIX_CPU_TIMERS_TASK_WORK; the use-after-free supports kernel memory disclosure, writes, and panic.
Summary
What happened
A race condition in Linux POSIX CPU timers allows local users to gain kernel privileges or crash the system through local syscalls. After an exiting non-autoreaping task passes exit_notify(), concurrent reaping and timer deletion can evade the firing-state check and leave a freed sigqueue linked for later kernel access. Exploitation requires local code execution and a kernel without CONFIG_POSIX_CPU_TIMERS_TASK_WORK; the use-after-free supports kernel memory disclosure, writes, and panic.
The record
- CVE
- CVE-2025-38352
- Published
- Jul 22, 2025
- Updated
- Sep 8, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-367, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 22, 2025CVE publishedPublication date reported by the CVE source.
- Sep 8, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <2c72fe18cc5f9f1750f5bc148cf1c94c29e106ff
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <2f3daa04a9328220de46f0d5c919a6c0073a9f0b
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <460188bc042a3f40f72d34b9f7fc6ee66b0b757b
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <764a7a5dfda23f69919441f2eac2a83e7db6e5bb
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <78a4b8e3795b31dae58762bc091bb0f4f74a2200
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <c076635b3a42771ace7d276de8dc3bc76ee2ba1b
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <c29d5318708e67ac13c1b6fc1007d179fb65b4d7
- Affected versionversion=0bdd2ed4138ec04e09b4f8165981efc99e439f55 <f90fff1e152dedf52b932240ebbd670d83330eca
- Affected versionversion=2.6.36
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Chronomalyfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- CISA Known Exploited Vulnerabilities catalog entryknown exploited catalog
Technologies
Your stack
See the directory against your own environment.
Your stack
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