What is CVE-2025-21851?

CVE-2025-21851 is a Low severity Linux kernel vulnerability with a CVSS score of 3.3 out of 10, classified as a Improper Locking flaw (CWE-667), affecting Linux kernel versions from 6.9 onward and patched in 6.12.17, 6.13.5 and 6.14. CVE-2025-21851 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2025-21851?

CVE-2025-21851 has a CVSS score of 3.3 out of 10, rated Low severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Is there a patch available for CVE-2025-21851?

Yes, CVE-2025-21851 has been patched. Fixed versions include 6.12.17, 6.13.5 and 6.14. If you are running Linux kernel 6.9 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2025-21851 actively exploited?

CVE-2025-21851 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-2025-21851

Low

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix softlockup in arena_map_free on 64k page kernel On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64. It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup. Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.

Package Linux Kernel

Published 2025-03-12

Last modified 2025-10-01

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

3.3

out of 10

Low

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

Low

Vector string

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

Weakness type

CWE-667

CVE-2025-21851 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 6.9 and later are affected. Fixed in 6.12.17, 6.13.5, 6.14 and their respective stable series.

Affected from

≥ 6.9

Fixed in

✓ 6.12.17 6.12.x ✓ 6.13.5 6.13.x ✓ 6.14

References

3 total

Kernel Git
https://git.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32b

Patch
Kernel Git
https://git.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1e

Patch
Kernel Git
https://git.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3

Patch

Details

CVE ID CVE-2025-21851

Severity Low

CVSS score 3.3 / 10

CVSS version 3.1

Published 2025-03-12

Modified 2025-10-01

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2025-21851?

CVE-2025-21851 is a Low severity Linux kernel vulnerability with a CVSS score of 3.3 out of 10 , classified as an Improper Locking flaw (CWE-667) . It affects Linux kernel versions from 6.9 onward and has been patched in 6.12.17, 6.13.5 and 6.14. CVE-2025-21851 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2025-21851?

CVE-2025-21851 has a CVSS score of 3.3 out of 10, rated Low 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:L.
Is there a patch available for CVE-2025-21851?

Yes. CVE-2025-21851 has been patched. Fixed versions include 6.12.17, 6.13.5 and 6.14. If you are running Linux kernel 6.9 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2025-21851 actively exploited?

No. CVE-2025-21851 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.