CVE-2026-98463
Received Received - Intake

Use SCX_RQ_IN_WAKEUP flag from core enqueue flags in Linux kernel

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Derive SCX_RQ_IN_WAKEUP from the core enqueue flags schedule_deferred_locked() skips scheduling a deferred action while SCX_RQ_IN_WAKEUP is set and relies on the task_woken_scx() call that follows a wakeup enqueue to run it. enqueue_task_scx() sets the flag from the merged enqueue flags, which include the flags stashed for a remote activation. move_remote_task_to_local_dsq() thus sets SCX_RQ_IN_WAKEUP on the destination rq when the moved task was woken up, although no task_woken_scx() follows that activation. An IMMED insert into a busy destination requests a local reenqueue during that enqueue. The request gets linked but not scheduled and stays pending until an unrelated wakeup or preemption on that CPU runs the deferred actions. The IMMED task sits behind the running task in the meantime. If nothing runs them before the scheduler is disabled, the request outlives the scheduler and points into its freed per-cpu area, which the next scheduler dereferences from run_deferred(). Test the core enqueue flags for the wakeup bit. Only the core's wakeup path is followed by task_woken_scx().

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98463
EUVD
EUVD-2026-103703

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
Linux Linux 997967adf10ce26c3e7bd89598b3ded62b943052
Linux Linux 57ccf5ccdc56954f2a91a7f66684fd31c566bde5
Linux Linux 57ccf5ccdc56954f2a91a7f66684fd31c566bde5
Linux Linux ee502c056c4c9cce4c132ccb588e06ffe5b831c1
Linux Linux 6.18.19
Linux Linux 6.19.9
Linux Linux 7.0

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a flaw in the sched_ext scheduler. It occurs when a task is moved between CPUs and the scheduler's deferred action handling is incorrectly triggered. This can lead to a use-after-free scenario where the scheduler dereferences freed memory, potentially causing system instability or crashes.

Impact Analysis

If exploited, this vulnerability could allow an attacker to crash the system or execute arbitrary code with kernel privileges. This may lead to denial of service, data corruption, or unauthorized access to sensitive information on affected Linux systems.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve this vulnerability. Monitor kernel logs for scheduler-related errors or crashes that may indicate exploitation.

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