VulnerabilityPublished 18 Oct 2026

CVE-2026-98463: Linux kernel · sched_ext: Derive SCX_RQ_IN_WAKEUP from the core enqueue flags

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in df5cdc2c832ca4e8a6d774596b9005558761a403 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · 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 df5cdc2c832ca4e8a6d774596b9005558761a403, 6c401ae426e20e53a3398a8e79afd0964c0f5110, 6.20 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.18.19 <6.18.55 >=6.19.9 <6.20	Fixed in df5cdc2c832ca4e8a6d774596b9005558761a403 6c401ae426e20e53a3398a8e79afd0964c0f5110 6.20 6.18.55 3fdf2ceb31e8aff77451e468bc8409e10587916a
LinuxLinux	Affected =7.0	Fixed in–

AI-suggested

A fix is available and has been applied in Linux kernel versions 6.18.55, 6.20, and later. Users and administrators should upgrade to these or later versions to remediate the issue. No additional mitigation steps are indicated by the vendor advisory.

Description

A scheduling flaw in the Linux kernel versions 6.18.19 through 6.18.54, 6.19.9 through 6.19.x, and version 7.0 allows deferred actions to remain pending indefinitely under certain conditions. This occurs because the scheduler's wakeup flag is incorrectly set from remote enqueue flags, causing deferred tasks to outlive the scheduler and potentially reference freed memory areas. The issue has been fixed in Linux kernel versions 6.18.55, 6.20, and later.

Impact

The flaw can cause deferred scheduling actions to remain pending indefinitely, leading to the scheduler referencing freed memory areas. This can result in undefined behavior or potential system instability. There is no indication of active exploitation in the wild. The impact is primarily on kernel stability and correctness rather than direct security compromise.

Summary

The Linux kernel's scheduler extension (sched_ext) had a vulnerability where the SCX_RQ_IN_WAKEUP flag was derived from merged enqueue flags including remote activation flags, leading to deferred actions not being scheduled as expected. Specifically, move_remote_task_to_local_dsq() sets SCX_RQ_IN_WAKEUP on the destination runqueue when a moved task was woken up, but no corresponding task_woken_scx() call follows. This causes IMMED insert requests to remain linked but unscheduled, potentially outliving the scheduler and referencing freed per-CPU memory areas during run_deferred() execution. The fix involves testing only the core enqueue flags for the wakeup bit to ensure proper scheduling of deferred actions.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 11:05 UTC

Technical details

References

Community reviews

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