VulnerabilityPublished 10 Aug 2026Updated 21 Oct 2026

CVE-2026-68421: Linux kernel · sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in e2f188cdbf8312289532c36eb4e9eb1c9544d43a : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:18 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e2f188cdbf8312289532c36eb4e9eb1c9544d43a, b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da, 6267ebee9f2f3e26f4968bf6dc29d350620fa320 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Aug 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to e2f188cdbf8312289532c36eb4e9eb1c9544d43a, b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da, 6267ebee9f2f3e26f4968bf6dc29d350620fa320 or 2907e9d0f05b506dfd58aec589a23042a56ef36b.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 7c65ae81ea86a6ed8086e1a5651acd766187f19b, < e2f188cdbf8312289532c36eb4e9eb1c9544d43a	Fixed in e2f188cdbf8312289532c36eb4e9eb1c9544d43a
LinuxLinux	Affected ≥ 7c65ae81ea86a6ed8086e1a5651acd766187f19b, < b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da	Fixed in b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da
LinuxLinux	Affected ≥ 7c65ae81ea86a6ed8086e1a5651acd766187f19b, < 6267ebee9f2f3e26f4968bf6dc29d350620fa320	Fixed in 6267ebee9f2f3e26f4968bf6dc29d350620fa320
LinuxLinux	Affected ≥ 7c65ae81ea86a6ed8086e1a5651acd766187f19b, < 2907e9d0f05b506dfd58aec589a23042a56ef36b	Fixed in 2907e9d0f05b506dfd58aec589a23042a56ef36b
LinuxLinux	Affected =6.12	Fixed in–

Description

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.

References

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