# CVE-2025-39964

## Summary

- **CVE ID:** CVE-2025-39964
- **Severity:** HIGH
- **CVSS Score:** 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Oct 13, 2025
- **Last Modified:** Sep 8, 2026

## Description

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.

## Affected Products

- Linux — Linux (8ff590903d5fc7f5a0a988c38267a3d08e6393a2)
- Linux — Linux (2.6.38)
- Linux — Linux (0)
- Linux — Linux (5.10.245)
- Linux — Linux (5.15.194)
- Linux — Linux (6.1.154)
- Linux — Linux (6.6.108)
- Linux — Linux (6.12.49)
- Linux — Linux (6.16.9)
- Linux — Linux (6.17)

## References

- [CNA](https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce)
- [CNA](https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9)
- [CNA](https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8)
- [CNA](https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84)
- [CNA](https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d)
- [CNA](https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042)
- [CNA](https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.32%
- **EPSS Percentile:** 25.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._