CVE-2025-39813: Linux kernel · ftrace: Fix potential warning in trace_printk_seq during ftrace_dump
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in fbd4cf7ee4db65ef36796769fe978e9eba6f0de4 : update Linux kernel when convenient.
Data as of 5 Nov 2026, 21:35 UTC
Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in fbd4cf7ee4db65ef36796769fe978e9eba6f0de4, f299353e7ccbcc5c2ed8993c48fbe7609cbe729a, e80ff23ba8bdb0f41a1afe2657078e4097d13a9a +5
Exploitation evidence
Disclosed: evidence found.
CVE published 16 Sep 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 5 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix is available and has been applied in the Linux kernel source code as indicated by the fixed commit versions. Users and administrators should update to a Linux kernel version that includes these fixes to prevent the race condition and associated warnings. No additional mitigation steps are required beyond applying the official fix.
Description
A race condition in the Linux kernel's ftrace subsystem could trigger a warning (WARN_ON_ONCE) during concurrent calls to ftrace_dump_one() and reading from trace_pipe. This occurs because the ring buffer data may be consumed by other readers between checks, causing an unpopulated iterator sequence and triggering the warning. The issue has been fixed by moving the trace_printk_seq() call to ensure the iterator sequence is properly populated before use.
References
- git.kernel.org/stable/c/f299353e7ccbcc5c2ed8993c48fbe7609cbe729a (opens in a new tab)
- git.kernel.org/stable/c/5ab0ec206deb99eb3baf8f1d7602aeaa91dbcc85 (opens in a new tab)
- git.kernel.org/stable/c/a6f0f8873cc30fd4543b09adf03f7f51d293f0e6 (opens in a new tab)
- git.kernel.org/stable/c/e80ff23ba8bdb0f41a1afe2657078e4097d13a9a (opens in a new tab)
- git.kernel.org/stable/c/28c8fb7ae2ad27d81c8de3c4fe608c509f6a18aa (opens in a new tab)
- git.kernel.org/stable/c/ced94e137e6cd5e79c65564841d3b7695d0f5fa3 (opens in a new tab)
- git.kernel.org/stable/c/fbd4cf7ee4db65ef36796769fe978e9eba6f0de4 (opens in a new tab)
- git.kernel.org/stable/c/4013aef2ced9b756a410f50d12df9ebe6a883e4a (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/10/msg00007.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-032379.html (opens in a new tab)