CVE-2026-68421 is a vulnerability in Linux Kernel
Published on August 10, 2026
sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()
put_prev_task_scx() warns when a runnable task drops to a lower sched_class
without SCX_OPS_ENQ_LAST, on the assumption that balance_one() would have
kept it running. Core scheduling breaks that: a forced-idle SMT sibling
reschedules through the core_pick fast path in pick_next_task(), which skips
pick_task_scx() and thus balance_one(), so a runnable task can drop to idle
with ENQ_LAST unset.
Gate the warning on sched_cpu_cookie_match(): a cookie mismatch means core
scheduling forced the idle, while a match (or core scheduling off) still
catches a genuine missing-ENQ_LAST drop.
Products Associated with CVE-2026-68421
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Affected Versions
Linux:- Version 7c65ae81ea86a6ed8086e1a5651acd766187f19b and below 2907e9d0f05b506dfd58aec589a23042a56ef36b is affected.
- Version 7c65ae81ea86a6ed8086e1a5651acd766187f19b and below e2f188cdbf8312289532c36eb4e9eb1c9544d43a is affected.
- Version 7c65ae81ea86a6ed8086e1a5651acd766187f19b and below b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da is affected.
- Version 6.12 is affected.
- Before 6.12 is unaffected.
- Version 6.18.42, <= 6.18.* is unaffected.
- Version 7.1.6, <= 7.1.* is unaffected.
- Version 7.2-rc4, <= * is unaffected.