Linux Kernel up to 7.1.8 sched_ext scx_cgroup_lock deadlock

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 7.1.8. This vulnerability affects the function scx_cgroup_lock of the component sched_ext. This manipulation causes deadlock. This vulnerability is registered as CVE-2026-74593. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.1.8 and classified as critical. Affected by this vulnerability is the function scx_cgroup_lock of the component sched_ext. The manipulation with an unknown input leads to a deadlock vulnerability. The CWE definition for the vulnerability is CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Take cgroup_lock() first in scx_cgroup_lock() scx_cgroup_lock() write-locks scx_cgroup_ops_rwsem and then takes cgroup_lock(), which can deadlock through kernfs: scx enable/disable cgroup rmdir cpu.weight write ------------------ ------------ ---------------- cgroup_lock() percpu_down_write(rwsem) cgroup_lock() kernfs_get_active() percpu_down_read(rwsem) kernfs_drain() The enable path waits for the rmdir to release cgroup_mutex. The rmdir, deactivating the cpu controller's files, waits in kernfs_drain() for the write's active reference. The write, in scx_group_set_weight(), waits for the rwsem behind the pending writer. Take cgroup_lock() first. The set_* paths take no cgroup locks inside the read side, so a pending write-lock then only waits for read sections that always run to completion, and no dependency from the rwsem back to cgroup_mutex remains.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-74593 since 08/15/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/22/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 7.1.9 eliminates this vulnerability. Applying the patch a054c9ffa9b7a0dffb763837b91ac9d381ec6d10/5f8b69642d18e1f3e11996707842ac530444e959 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.1.6
• 7.1.7
• 7.1.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

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