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CVE-2025-21851

7.8 · HIGH

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 ca…

Published Mar 12, 2025CWE-667EPSS 0.18%

Overview

CVE-2025-21851 is a high-severity vulnerability. It was published on March 12, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/517e8a7835e8cfb398a0aeb0133de50e31cae32bRefgit.kernel.org/stable/c/787d556a3de447e70964a4bdeba9196f62a62b1eRefgit.kernel.org/stable/c/c1f3f3892d4526f18aaeffdb6068ce861e793ee3

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21851?

CVE-2025-21851 is a high-severity vulnerability. It was published on March 12, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-21851?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-21851?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-21851?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21851 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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