CVE-2025-21895: Linux kernel · Race Condition
Source GCVE Database
Not known to be exploited · CVSS 4.7 Medium.
Data as of 29 Oct 2026, 23:33 UTC
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
A fix has been implemented in the Linux kernel to correctly order the PMU context list and eliminate the warning. Users should apply the official kernel update that includes this fix once available. Since this is a kernel-level issue, upgrading to the fixed kernel version is the recommended remediation. No other mitigation or workaround is indicated.
Description
CVE-2025-21895 is a medium-severity vulnerability in the Linux kernel's perf subsystem related to unordered perf_event_pmu_context lists. The issue causes warnings triggered by mismatched ordering of PMU context lists between parent and child processes, which can lead to instability or crashes. The problem arises because the order of PMU contexts in the parent and child differ due to how events are added and inherited. A fix was implemented to insert the PMU context in the correct order to resolve this warning.
References
- nvd.nist.gov/vuln/detail/CVE-2025-21895 (opens in a new tab)
- git.kernel.org/stable/c/2016066c66192a99d9e0ebf433789c490a6785a2 (opens in a new tab)
- git.kernel.org/stable/c/3e812a70732d84b7873cea61a7f6349b9a9dcbf5 (opens in a new tab)
- git.kernel.org/stable/c/7d582eb6e4e100959ba07083d7563453c8c2a343 (opens in a new tab)
- git.kernel.org/stable/c/f0c3971405cef6892844016aa710121a02da3a23 (opens in a new tab)