What is CVE-2025-21966?

CVE-2025-21966 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Out-of-bounds Write flaw (CWE-787), affecting Linux kernel versions from 6.5 onward and patched in 6.6.84, 6.12.20, 6.13.8 and others. CVE-2025-21966 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21966?

CVE-2025-21966 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2025-21966?

Yes, CVE-2025-21966 has been patched. Fixed versions include 6.6.84, 6.12.20, 6.13.8 and others. If you are running Linux kernel 6.5 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21966 actively exploited?

CVE-2025-21966 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Out-of-bounds Write (CWE-787)?

The product writes data past the end or before the beginning of the intended buffer. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/787.html

CVE-2025-21966

High

In the Linux kernel, the following vulnerability has been resolved: dm-flakey: Fix memory corruption in optional corrupt_bio_byte feature Fix memory corruption due to incorrect parameter being passed to bio_init

Package Linux Kernel

Published 2025-04-01

Last modified 2025-10-01

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

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

Weakness type

CWE-787

CVE-2025-21966 is a Out-of-bounds Write vulnerability

What is Out-of-bounds Write?

The product writes data past the end or before the beginning of the intended buffer. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.5 and later are affected. Fixed in 6.6.84, 6.12.20, 6.13.8, 6.14 and their respective stable series.

Affected from

≥ 6.5

Fixed in

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

References

4 total

Kernel Git
https://git.kernel.org/stable/c/57e9417f69839cb10f7ffca684c38acd28ceb57b

Patch
Kernel Git
https://git.kernel.org/stable/c/5a87e46da2418c57b445371f5ca0958d5779ba5f

Patch
Kernel Git
https://git.kernel.org/stable/c/818330f756f3800c37d738bd36bce60eac949938

Patch
Kernel Git
https://git.kernel.org/stable/c/da070843e153471be4297a12fdaa64023276f40e

Patch

Details

CVE ID CVE-2025-21966

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2025-04-01

Modified 2025-10-01

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21966?

CVE-2025-21966 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Out-of-bounds Write flaw (CWE-787) . It affects Linux kernel versions from 6.5 onward and has been patched in 6.6.84, 6.12.20, 6.13.8 and others. CVE-2025-21966 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21966?

CVE-2025-21966 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2025-21966?

Yes. CVE-2025-21966 has been patched. Fixed versions include 6.6.84, 6.12.20, 6.13.8 and others. If you are running Linux kernel 6.5 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21966 actively exploited?

No. CVE-2025-21966 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.