VulnerabilityPublished 28 Oct 2026

CVE-2026-99104: Linux kernel · sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor

Affects Linux kernelSource CVE Database V5

Not known to be exploited : upgrade to f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7 or 5bdeca322a6f8d10acaf67cccab1f69747ee7be3 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 f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7, 5bdeca322a6f8d10acaf67cccab1f69747ee7be3

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 f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7 or 5bdeca322a6f8d10acaf67cccab1f69747ee7be3.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ aa2a0a19686c90106ade6a7e848ffbb62d55d733, < f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7	Fixed in f0f18075e45d47bef7ff2eb9512ee4f0c7e5f9c7
LinuxLinux	Affected ≥ aa2a0a19686c90106ade6a7e848ffbb62d55d733, < 5bdeca322a6f8d10acaf67cccab1f69747ee7be3	Fixed in 5bdeca322a6f8d10acaf67cccab1f69747ee7be3
LinuxLinux	Affected =7.1	Fixed in–

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.

References

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