VulnerabilityPublished 18 Jun 2025Updated 5 Nov 2026

CVE-2025-38067: Linux kernel · rseq: Fix segfault on registration when rseq_cs is non-zero

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in fd881d0a085fc54354414aed990ccf05f282ba53 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:19 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

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 fd881d0a085fc54354414aed990ccf05f282ba53, f004f58d18a2d3dc761cf973ad27b4a5997bd876, eaf112069a904b6207b4106ff083e0208232a2eb +4

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jun 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < fd881d0a085fc54354414aed990ccf05f282ba53	Fixed in fd881d0a085fc54354414aed990ccf05f282ba53
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < f004f58d18a2d3dc761cf973ad27b4a5997bd876	Fixed in f004f58d18a2d3dc761cf973ad27b4a5997bd876
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < eaf112069a904b6207b4106ff083e0208232a2eb	Fixed in eaf112069a904b6207b4106ff083e0208232a2eb
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < b2b05d0dc2f4f0646922068af435aed5763d16ba	Fixed in b2b05d0dc2f4f0646922068af435aed5763d16ba
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < 48900d839a3454050fd5822e34be8d54c4ec9b86	Fixed in 48900d839a3454050fd5822e34be8d54c4ec9b86
LinuxLinux	Affected ≥ d7822b1e24f2df5df98c76f0e94a5416349ff759, < 3e4028ef31b69286c9d4878cee0330235f53f218	Fixed in 3e4028ef31b69286c9d4878cee0330235f53f218

Description

In the Linux kernel, the following vulnerability has been resolved: rseq: Fix segfault on registration when rseq_cs is non-zero The rseq_cs field is documented as being set to 0 by user-space prior to registration, however this is not currently enforced by the kernel. This can result in a segfault on return to user-space if the value stored in the rseq_cs field doesn't point to a valid struct rseq_cs. The correct solution to this would be to fail the rseq registration when the rseq_cs field is non-zero. However, some older versions of glibc will reuse the rseq area of previous threads without clearing the rseq_cs field and will also terminate the process if the rseq registration fails in a secondary thread. This wasn't caught in testing because in this case the leftover rseq_cs does point to a valid struct rseq_cs. What we can do is clear the rseq_cs field on registration when it's non-zero which will prevent segfaults on registration and won't break the glibc versions that reuse rseq areas on thread creation.

References

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