CVEvulnerability

CVE-2025-39964

5.5 MEDIUM Known exploited Published 2025-10-13 Modified 2026-10-19 Official page ↗

CISA Known Exploited Vulnerability

Linux Kernel Race Condition Vulnerability — Linux Kernel

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.

Added to KEV
2026-09-18
Remediation due
2026-09-21
Ransomware use
Unknown
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.
Notes
This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce; https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9; https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8; https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84; https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d; https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042; https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2025-39964
Status
Analyzed
Published
2025-10-13
Last modified
2026-10-19
Assigner
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS 3.1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)
7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1 ([email protected])
5.5 MEDIUM — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-362

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 configurations

• linux linux kernel (>= 2.6.38 < 5.10.245) • linux linux kernel (>= 5.11 < 5.15.194) • linux linux kernel (>= 5.16 < 6.1.154) • linux linux kernel (>= 6.2 < 6.6.108) • linux linux kernel (>= 6.7 < 6.12.49) • linux linux kernel (>= 6.13 < 6.16.9) • linux linux kernel 6.17 • siemens simatic s7-1500 cpu 1518-4 pn\/dp mfp firmware (>= 3.1.6) • siemens simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware (>= 3.1.6)

Related

Weakness · CWE (1)

  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization weakness

References