What is CVE-2025-21955?

CVE-2025-21955 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, affecting Linux kernel versions from 5.15 onward and patched in 6.6.84, 6.12.20, 6.13.8 and others. CVE-2025-21955 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21955?

CVE-2025-21955 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-2025-21955?

Yes, CVE-2025-21955 has been patched. Fixed versions include 6.6.84, 6.12.20, 6.13.8 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21955 actively exploited?

CVE-2025-21955 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

CVE-2025-21955

Medium

In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent connection release during oplock break notification ksmbd_work could be freed when after connection release. Increment r_count of ksmbd_conn to indicate that requests are not finished yet and to not release the connection.

Package Linux Kernel

Published 2025-04-01

Last modified 2025-10-31

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

Affected versions

Linux kernel versions 5.15 and later are affected. Fixed in 6.6.84, 6.12.20, 6.13.8, 6.14 and their respective stable series.

Affected from

≥ 5.15

Fixed in

✓ 6.6.84 6.6.x ✓ 6.12.20 6.12.x ✓ 6.13.8 6.13.x ✓ 6.14

References

The following references provide additional information about CVE-2025-21955 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

Kernel patch commit
https://git.kernel.org/stable/c/09aeab68033161cb54f194da93e51a11aee6144b
Patch
Kernel patch commit
https://git.kernel.org/stable/c/3aa660c059240e0c795217182cf7df32909dd917
Patch
Kernel patch commit
https://git.kernel.org/stable/c/a4261bbc33fbf99b99c80aa3a2c5097611802980
Patch

4 patch commits total View all on NVD

Details

CVE ID CVE-2025-21955

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-04-01

Modified 2025-10-31

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21955?

CVE-2025-21955 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 5.15 onward and has been patched in 6.6.84, 6.12.20, 6.13.8 and others. CVE-2025-21955 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21955?

CVE-2025-21955 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-2025-21955?

Yes — CVE-2025-21955 has been patched. Fixed versions include 6.6.84, 6.12.20, 6.13.8 and others. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21955 actively exploited?

No — CVE-2025-21955 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.