#VU103011 Use-after-free in Linux kernel - CVE-2025-21631

Vulnerability identifier: #VU103011

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-21631

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the bfq_waker_bfqq() function in block/bfq-iosched.c. A local user can escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

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External links
https://git.kernel.org/stable/c/2550149fcdf2934155ff625d76ad4e3d4b25bbc6
https://git.kernel.org/stable/c/bc2aeb35ff167e0c6b0cedf0c96a5c41e6cba1ed
https://git.kernel.org/stable/c/be3eed59ac01f429ac10aaa46e26f653bcf581ab
https://git.kernel.org/stable/c/fcede1f0a043ccefe9bc6ad57f12718e42f63f1d

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.