Known exploited vulnerability · Linux

CVE-2025-39964: Linux Kernel Race Condition Vulnerability

mediumCVSS 3.1 5.5Exploited

In the Linux kernel, the following vulnerability has been resolved: crypto: afalg - Disallow concurrent writes in afalgsendmsg Issuing two writes to the same afalg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state.

Published Oct 13, 2025 · Updated Oct 19, 2026

Required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Advisory details

From the National Vulnerability Database. This product uses the NVD API but is not endorsed or certified by the NVD.

In the Linux kernel, the following vulnerability has been resolved:

crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg

Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state.

Disallow this by adding a new ctx->write field that indiciates exclusive ownership for writing.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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