Task stalls via dispatch-state overwrite race
Published Oct 18, 2026 · Updated Oct 18, 2026
A race in Linux sched_ext 7.1 allows attackers to stall tasks through concurrent dispatch and reenqueue operations. Reenqueue paths run ops.enqueue() before scx_dispatch_enqueue() finishes, allowing its final SCX_OPSS_NONE store to overwrite SCX_OPSS_QUEUED so finish_dispatch() rejects later dispatches. Exposure requires a running BPF scheduler and the racing operations; upstream documentation describes fallback to fair scheduling when stalled runnable tasks are detected, rather than an unrecoverable system hang.
Summary
What happened
A race in Linux sched_ext 7.1 allows attackers to stall tasks through concurrent dispatch and reenqueue operations. Reenqueue paths run ops.enqueue() before scx_dispatch_enqueue() finishes, allowing its final SCX_OPSS_NONE store to overwrite SCX_OPSS_QUEUED so finish_dispatch() rejects later dispatches. Exposure requires a running BPF scheduler and the racing operations; upstream documentation describes fallback to fair scheduling when stalled runnable tasks are detected, rather than an unrecoverable system hang.
The record
- CVE
- CVE-2026-98864
- Published
- Oct 18, 2026
- Updated
- Oct 18, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Oct 18, 2026CVE publishedPublication date reported by the CVE source.
- Oct 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=7.1
- Affected versionversion=ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d <43457bf6550044c40bd6d3fcdf9ea66f5a55d139
- Affected versionversion=ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d <7de9a6fb44eae4f05e68c805d58b9c618815adfa
What conditions does exploitation require?
What is affected?
Published CVSS scores
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CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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