Linux Kernel up to 6.18.21/6.19.11 sched_ext trampoline.c is_bpf_migration_disabled privilege escalation

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.21/6.19.11 and classified as problematic. This vulnerability affects the function is_bpf_migration_disabled of the file trampoline.c of the component sched_ext. Executing a manipulation can lead to an unknown weakness. This vulnerability is handled as CVE-2026-31734. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.21/6.19.11 and classified as problematic. This vulnerability affects the function is_bpf_migration_disabled of the file trampoline.c of the component sched_ext. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU Since commit 8e4f0b1ebcf2 ("bpf: use rcu_read_lock_dont_migrate() for trampoline.c"), the BPF prolog (__bpf_prog_enter) calls migrate_disable() only when CONFIG_PREEMPT_RCU is enabled, via rcu_read_lock_dont_migrate(). Without CONFIG_PREEMPT_RCU, the prolog never touches migration_disabled, so migration_disabled == 1 always means the task is truly migration-disabled regardless of whether it is the current task. The old unconditional p == current check was a false negative in this case, potentially allowing a migration-disabled task to be dispatched to a remote CPU and triggering scx_error in task_can_run_on_remote_rq(). Only apply the p == current disambiguation when CONFIG_PREEMPT_RCU is enabled, where the ambiguity with the BPF prolog still exists.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-31734 since 03/09/2026. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/01/2026).

Upgrading to version 6.18.22 or 6.19.12 eliminates this vulnerability. Applying the patch 72c43eb2e334febe93018cfb68ae828f55c6e49e/b4992a9446bb9a639007bfd32bf5c5a7e30199e5/0c4a59df370bea245695c00aaae6ae75747139bd 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.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1346). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux
• Microsoft Azure Linux
• Red Hat OpenShift

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
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 6.19.7
• 6.19.8
• 6.19.9
• 6.19.10
• 6.19.11

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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