CVE-2026-31734: Linux kernel · sched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 27 Oct 2026, 00:07 UTC
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
Description
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-31734 (opens in a new tab)
- git.kernel.org/stable/c/0c4a59df370bea245695c00aaae6ae75747139bd (opens in a new tab)
- git.kernel.org/stable/c/72c43eb2e334febe93018cfb68ae828f55c6e49e (opens in a new tab)
- git.kernel.org/stable/c/b4992a9446bb9a639007bfd32bf5c5a7e30199e5 (opens in a new tab)