What is CVE-2025-21817?

CVE-2025-21817 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a Improper Locking flaw (CWE-667), affecting Linux kernel versions from 6.12.96 onward and patched in 6.13 and 6.13.3. CVE-2025-21817 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21817?

CVE-2025-21817 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-2025-21817?

Yes, CVE-2025-21817 has been patched. Fixed versions include 6.13 and 6.13.3. If you are running Linux kernel 6.12.96 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21817 actively exploited?

CVE-2025-21817 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Improper Locking (CWE-667)?

The product does not properly acquire or release a lock, which can lead to unexpected behaviour. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/667.html

CVE-2025-21817

Medium

In the Linux kernel, the following vulnerability has been resolved: block: mark GFP_NOIO around sysfs ->store() sysfs ->store is called with queue freezed, meantime we have several ->store() callbacks(update_nr_requests, wbt, scheduler) to allocate memory with GFP_KERNEL which may run into direct reclaim code path, then potential deadlock can be caused. Fix the issue by marking NOIO around sysfs ->store()

Package Linux Kernel

Published 2025-02-27

Last modified 2026-07-18

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-667

CVE-2025-21817 is a Improper Locking vulnerability

What is Improper Locking?

The product does not properly acquire or release a lock, which can lead to unexpected behaviour. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.12.96, 6.13.2 and later are affected. Fixed in 6.13, 6.13.3 and their respective stable series.

Affected from

≥ 6.12.96 ≥ 6.13.2

Fixed in

✓ 6.13 6.13.x ✓ 6.13.3 6.13.x

References

2 total

Kernel Git
https://git.kernel.org/stable/c/2566ce907e5d5db8a039647208e029ce559baa31

Patch
Kernel Git
https://git.kernel.org/stable/c/7c0be4ead1f8f5f8be0803f347de0de81e3b8e1c

Patch

Details

CVE ID CVE-2025-21817

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2025-02-27

Modified 2026-07-18

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21817?

CVE-2025-21817 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as an Improper Locking flaw (CWE-667) . It affects Linux kernel versions from 6.12.96 onward and has been patched in 6.13 and 6.13.3. CVE-2025-21817 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21817?

CVE-2025-21817 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-2025-21817?

Yes. CVE-2025-21817 has been patched. Fixed versions include 6.13 and 6.13.3. If you are running Linux kernel 6.12.96 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21817 actively exploited?

No. CVE-2025-21817 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.