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CVE-2025-21631

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: block, bfq: fix waker_bfqq UAF after bfq_split_bfqq() Our syzkaller report a following UAF for v6.6: BUG: KASAN: slab-use-afte…

Published Jan 19, 2025CWE-416EPSS 0.21%

Overview

CVE-2025-21631 is a high-severity vulnerability. It was published on January 19, 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:

block, bfq: fix waker_bfqq UAF after bfq_split_bfqq()

Our syzkaller report a following UAF for v6.6:

BUG: KASAN: slab-use-after-free in bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958

Read of size 8 at addr ffff8881b57147d8 by task fsstress/232726

CPU: 2 PID: 232726 Comm: fsstress Not tainted 6.6.0-g3629d1885222 #39

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:88 [inline]

dump_stack_lvl+0x91/0xf0 lib/dump_stack.c:106

print_address_description.constprop.0+0x66/0x300 mm/kasan/report.c:364

print_report+0x3e/0x70 mm/kasan/report.c:475

kasan_report+0xb8/0xf0 mm/kasan/report.c:588

hlist_add_head include/linux/list.h:1023 [inline]

bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958

bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271

bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323

blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660

blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143

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/2550149fcdf2934155ff625d76ad4e3d4b25bbc6Refgit.kernel.org/stable/c/bc2aeb35ff167e0c6b0cedf0c96a5c41e6cba1edRefgit.kernel.org/stable/c/be3eed59ac01f429ac10aaa46e26f653bcf581abRefgit.kernel.org/stable/c/f587c1ac68956c4703857d650d9b1cd7bb2ac4d7Refgit.kernel.org/stable/c/fcede1f0a043ccefe9bc6ad57f12718e42f63f1dReflists.debian.org/debian-lts-announce/2025/03/msg00001.html

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21631?

CVE-2025-21631 is a high-severity vulnerability. It was published on January 19, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-21631?

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-2025-21631?

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-2025-21631?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21631 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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