# CVE-2026-98864: Linux kernel sched_ext task reenqueue state synchronization

Source: https://junglewise.ai/threats/cve-2026-98864-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-18. Updated: 2026-10-18  
License: CC BY 4.0 with a link back

CVE-2026-98864 · Severity: info · Published 2026-10-18

The Linux kernel's sched_ext scheduler contains a race condition in task reenqueuing logic. When a task is reenqueued before a dispatcher's state update completes, the scheduler can lose track of the task's queued state, causing subsequent dispatches to be dropped and tasks to hang or fail to execute.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-98864 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-98864 being exploited in the wild.

**How severe is CVE-2026-98864?** Informational severity, published 18 October 2026.

**Which products and versions are affected?** Linux Kernel v7.1 and later.

**Is there a fix for CVE-2026-98864?** A patch was published on 2026-09-30. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-98864 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-98864?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A race exists in the sched_ext scheduler's reenqueue paths (reenq_local, reenq_user, scx_reenq_reject) where tasks can be processed before the dispatcher finishes setting the final SCX_OPSS_DISPATCHING state. When reenqueue runs ops.enqueue() and sets SCX_OPSS_QUEUED before the dispatcher's final store lands, the dispatcher's SCX_OPSS_NONE overwrites it, causing finish_dispatch() to drop all subsequent dispatches of that task. The fix adds synchronization points to wait for SCX_OPSS_DISPATCHING to clear before processing reenqueue operations, matching the behavior of the dequeue path.

## Affected products

- Linux Linux kernel v7.1 and later

## Timeline

- 2026-09-15: disclosed
- 2026-09-30: patched

## References

- [https://git.kernel.org/stable/c/43457bf6550044c40bd6d3fcdf9ea66f5a55d139](https://git.kernel.org/stable/c/43457bf6550044c40bd6d3fcdf9ea66f5a55d139)
- [https://git.kernel.org/stable/c/7de9a6fb44eae4f05e68c805d58b9c618815adfa](https://git.kernel.org/stable/c/7de9a6fb44eae4f05e68c805d58b9c618815adfa)

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