SB20260912263 - Race condition in Linux kernel sched ext

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-89517)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 6.8 [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]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a race condition in the sched_ext core scheduling task-selection logic when task selections interleave after dispatch releases the runqueue lock. A local user can trigger a cookied ping-pong workload to cause a denial of service.

Exploitation requires core scheduling on an SMT system.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/cdafb68155bee2d5c4e50c12e4606323e9334e6b
• https://git.kernel.org/stable/c/d954004205c1a1d3f59ce8482b559266c15600fa