SB2026102381 - Deadlock in Linux kernel sched

Description

This security bulletin contains information about 1 vulnerability.

1) Deadlock (CVE-ID: CVE-2026-99085)

CWE-ID: CWE-833 - Deadlock

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/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 by hanging CPU hotplug operations.

The vulnerability exists due to improper synchronization in the Linux kernel sched_ext scheduler when offlining a CPU whose tasks remain in a user dispatch queue or are held by the BPF scheduler. A local user can trigger the affected scheduling conditions during CPU offlining to prevent the hotplug thread from completing, potentially leaving cpu_down() hung while holding cpu_hotplug_lock and causing a denial of service.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/173ff9d03ec6373c3158b6e630af33a9b36fd216
• https://git.kernel.org/stable/c/638ee6bca19750934ea13f9c325f46fd8ae60064
• https://git.kernel.org/stable/c/d35a535d3e3e71f92a051d94e415f43612c4edfc
• https://git.kernel.org/stable/c/f79cd7a2df3768323fbfb9b0f96adff08fb7eb4c