Linux Kernel up to 6.18.31/7.0.6/7.1-rc1 sched_ext scx_cgroup_ops_rwsem use after free

Summaryinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.18.31/7.0.6/7.1-rc1. Affected by this issue is the function scx_cgroup_ops_rwsem of the component sched_ext. This manipulation causes use after free. This vulnerability is handled as CVE-2026-46154. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.31/7.0.6/7.1-rc1. It has been declared as critical. Affected by this vulnerability is the function scx_cgroup_ops_rwsem of the component sched_ext. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Read scx_root under scx_cgroup_ops_rwsem in cgroup setters scx_group_set_{weight,idle,bandwidth}() cache scx_root before acquiring scx_cgroup_ops_rwsem, so the pointer can be stale by the time the op runs. If the loaded scheduler is disabled and freed (via RCU work) and another is enabled between the naked load and the rwsem acquire, the reader sees scx_cgroup_enabled=true (the new scheduler's) but dereferences the freed one - UAF on SCX_HAS_OP(sch, ...) / SCX_CALL_OP(sch, ...). scx_cgroup_enabled is toggled only under scx_cgroup_ops_rwsem write (scx_cgroup_{init,exit}), so reading scx_root inside the rwsem read section correlates @sch with the enabled snapshot.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-46154 since 05/13/2026. The exploitation appears to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 06/10/2026).

Upgrading to version 6.18.32, 7.0.7 or 7.1-rc2 eliminates this vulnerability. Applying the patch ce9aaa3af445c391735c9d000c4db60dfd5640d4/0f54f6355575971673d8aac7da107ec4178e45bd/80afd4c84bc8f5e80145ce35279f5ce53f6043db is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.1-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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