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

The following references provide additional information about CVE-2025-21851 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

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.

  • What is Improper Locking (CWE-667)?

    The product does not properly acquire or release a lock, which can lead to unexpected behaviour. View CWE-667 on MITRE CWE →

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