What is CVE-2025-39931?

CVE-2025-39931 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 2.6.38 onward and patched in 6.1.154, 6.6.108, 6.12.49 and others. CVE-2025-39931 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-39931?

CVE-2025-39931 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2025-39931?

Yes, CVE-2025-39931 has been patched. Fixed versions include 6.1.154, 6.6.108, 6.12.49 and others. If you are running Linux kernel 2.6.38 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-39931 actively exploited?

CVE-2025-39931 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-39931

Medium

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.

Package Linux Kernel

Published 2025-10-04

Last modified 2026-05-12

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

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

Weakness type

CWE-908

CVE-2025-39931 is classified as CWE-908

See CWE-908 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 2.6.38 and later are affected. Fixed in 6.1.154, 6.6.108, 6.12.49, 6.16.9, 6.17 and their respective stable series.

Affected from

≥ 2.6.38

Fixed in

✓ 6.1.154 6.1.x ✓ 6.6.108 6.6.x ✓ 6.12.49 6.12.x ✓ 6.16.9 6.16.x ✓ 6.17

References

The following references provide additional information about CVE-2025-39931 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Cert-Portal
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
Kernel patch commit
https://git.kernel.org/stable/c/045ee26aa3920a47ec46d7fcb302420bf01fd753
Patch
Kernel patch commit
https://git.kernel.org/stable/c/2374c11189ef704a3e4863646369f1b8e6a27d71
Patch
Kernel patch commit
https://git.kernel.org/stable/c/24c1106504c625fabd3b7229611af617b4c27ac7
Patch

5 patch commits total View all on NVD

Details

CVE ID CVE-2025-39931

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-10-04

Modified 2026-05-12

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-39931?

CVE-2025-39931 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.38 onward and has been patched in 6.1.154, 6.6.108, 6.12.49 and others. CVE-2025-39931 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-39931?

CVE-2025-39931 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2025-39931?

Yes — CVE-2025-39931 has been patched. Fixed versions include 6.1.154, 6.6.108, 6.12.49 and others. If you are running Linux kernel 2.6.38 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-39931 actively exploited?

No — CVE-2025-39931 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.