What is CVE-2025-39964?

CVE-2025-39964 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a Race Condition flaw (CWE-362), affecting Linux kernel versions from 2.6.38 onward and patched in 5.10.245, 5.15.194, 6.1.154 and others. CVE-2025-39964 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild.

What is the CVSS score for CVE-2025-39964?

CVE-2025-39964 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-2025-39964?

Yes, CVE-2025-39964 has been patched. Fixed versions include 5.10.245, 5.15.194, 6.1.154 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-2025-39964 actively exploited?

Yes. CVE-2025-39964 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild with a CVSS score of 5.5 (Medium severity).

What is Race Condition (CWE-362)?

The product contains a code sequence that can run concurrently with other code, creating unexpected states. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/362.html

CVE-2025-39964

Medium KEV — Actively Exploited

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.

Package Linux Kernel

Published 2025-10-13

Last modified 2026-10-19

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-362

CVE-2025-39964 is a Race Condition vulnerability

What is Race Condition?

The product contains a code sequence that can run concurrently with other code, creating unexpected states. Learn more on MITRE CWE

Affected versions

Linux kernel versions 2.6.38 and later are affected. Fixed in 5.10.245, 5.15.194, 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

✓ 5.10.245 5.10.x ✓ 5.15.194 5.15.x ✓ 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

10 total

CISA
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39964

US Government Resource
Kernel Git
https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce

Patch
Kernel Git
https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285

Patch
Kernel Git
https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8

Patch
Kernel Git
https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042

Patch

Showing 5 of 10 references View all on NVD

Details

CVE ID CVE-2025-39964

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-10-13

Modified 2026-10-19

KEV Yes

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-39964?

CVE-2025-39964 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a Race Condition flaw (CWE-362) . It affects Linux kernel versions from 2.6.38 onward and has been patched in 5.10.245, 5.15.194, 6.1.154 and others. CVE-2025-39964 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild.
What is the CVSS score for CVE-2025-39964?

CVE-2025-39964 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-2025-39964?

Yes. CVE-2025-39964 has been patched. Fixed versions include 5.10.245, 5.15.194, 6.1.154 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-2025-39964 actively exploited?

Yes. CVE-2025-39964 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. It carries a CVSS score of 5.5 (Medium severity).