CVE entry · CVE-2025-39964
CVE-2025-39964: Linux Kernel Race Condition Vulnerability
Linux Kernel contains a race condition vulnerability which allows concurrent writes to the same AF_ALG socket causing data to be unpredictably interleaved and creating inconsistencies in the socket's internal state.
- Actively exploited: added to CISA’s KEV catalog on September 18, 2026.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: September 21, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes Linux Kernel, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- Vendor advisory or reference cited by CISA (git.kernel.org)
- NVD entry (NIST)
- CISA KEV catalog
Other Linux vulnerabilities
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Linux Kernel Out-of-Bounds Write Vulnerability
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Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
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Linux Kernel Unspecified Vulnerability
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Linux Kernel Out-of-Bounds Write Vulnerability
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Linux Kernel Improper Authentication Vulnerability
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Linux Kernel Incorrect Resource Transfer Between Spheres Vulnerability