CVE-2026-99104
Received
Received - Intake
Linux Kernel sched_ext Bypass Dispatch Claim Vulnerability
Vulnerability report for CVE-2026-99104, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-28
Last updated on: 2026-10-28
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor
scx_bypass() claims bypass dispatch when the scheduler's depth goes from
zero to one and releases it when the depth returns to zero, but propagates
only the depth to the descendants, not the claim. A descendant that starts
bypassing with its ancestor never claims, and one whose own bypass ends
under the ancestor's keeps its claim, as its depth does not return to zero.
A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its
claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next
bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that
starts under a PM suspend has no claim, so once the resume lifts the root's
bypass its tasks sit on the parent's bypass DSQs with nobody consuming them.
Claim for every descendant whose depth goes from zero to one in the
propagation and release every scheduler in the subtree whose depth returned
to zero once the tasks have moved out of the bypass DSQs. A parent that is
bypassing itself when a descendant claims consumes only its own bypass DSQs,
empty until it leaves bypass and becomes the host.
CVSS Scores
EPSS Scores
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Meta Information
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
