CVE-2025-39931: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-908 CWE-908

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.38 — 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	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/045ee26aa3920a47ec46d7fcb302420bf01fd753 https://git.kernel.org/stable/c/2374c11189ef704a3e4863646369f1b8e6a27d71 https://git.kernel.org/stable/c/24c1106504c625fabd3b7229611af617b4c27ac7 https://git.kernel.org/stable/c/6241b9e2809b12da9130894cf5beddf088dc1b8a https://git.kernel.org/stable/c/9574b2330dbd2b5459b74d3b5e9619d39299fc6f

Other References

https://cert-portal.siemens.com/productcert/html/ssa-082556.html

Frequently Asked Questions

What is CVE-2025-39931? +

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-39931? +

CVE-2025-39931 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-39931? +

CVE-2025-39931 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-39931? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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