VulnerabilityPublished 28 Oct 2026

CVE-2026-99105: Linux kernel · sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59, 8d891c218016b6145993e082e7f732cb69dd0e29, 7a9df76679633cf26e0fea882a684012c6ec245a

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 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 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59, 8d891c218016b6145993e082e7f732cb69dd0e29 or 7a9df76679633cf26e0fea882a684012c6ec245a.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ f0e1a0643a59bf1f922fa209cec86a170b784f3f, < 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59	Fixed in 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59
LinuxLinux	Affected ≥ f0e1a0643a59bf1f922fa209cec86a170b784f3f, < 8d891c218016b6145993e082e7f732cb69dd0e29	Fixed in 8d891c218016b6145993e082e7f732cb69dd0e29
LinuxLinux	Affected ≥ f0e1a0643a59bf1f922fa209cec86a170b784f3f, < 7a9df76679633cf26e0fea882a684012c6ec245a	Fixed in 7a9df76679633cf26e0fea882a684012c6ec245a
LinuxLinux	Affected =6.12	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ With SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to ops.enqueue() instead of being kept running. Exiting tasks without SCX_OPS_ENQ_EXITING, migration disabled tasks without SCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue() and go straight to the local DSQ. This happens in put_prev_task_scx() after the pick has settled on idle, so nothing reschedules the CPU, which idles with the task queued until an unrelated wakeup lands on it or the watchdog fires. scx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit this during mass cgroup teardown: exiting tasks stuck in exit_mmap() for over 40 seconds. A task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST enqueue left the task on this CPU's local DSQ, set need_resched on the task being switched in, as proxy_resched_idle() does. resched_curr() would flag the task being put instead, and __schedule() clears that right after the pick.

References

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