Improper locking in Linux kernel sched

1) Improper locking

EUVDB-ID: #VU103128

Risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-21657

CWE-ID: CWE-667 - Improper Locking

Exploit availability: No

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper locking within the scx_ops_bypass() function in kernel/sched/ext.c. A local user can perform a denial of service (DoS) attack.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Linux kernel: 6.12 - 6.12.9

CPE2.3

• cpe:2.3:o:linux_foundation:linux_kernel:6.12:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.1:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.2:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.3:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.4:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.5:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.6:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.7:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.8:*:*:*:*:*:*:*
• cpe:2.3:o:linux_foundation:linux_kernel:6.12.9:*:*:*:*:*:*:*

External links

https://git.kernel.org/stable/c/6268d5bc10354fc2ab8d44a0cd3b042d49a0417e
https://git.kernel.org/stable/c/d9e446dd63cee7161717a6a8414ba9c6435af764
https://mirrors.edge.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.12.10

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.