# CVE-2026-98865: sched_ext: Don't run ops.dequeue() with a DSQ lock held

> A local attacker with BPF scheduler privileges can cause a kernel deadlock by triggering a self-deadlock in the sched_ext subsystem.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98865, GHSA-2w8f-349m-66qf, UBUNTU-CVE-2026-98865

## What is CVE-2026-98865?

CVE-2026-98865 is a denial of service vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

sched_ext: Don't run ops.dequeue() with a DSQ lock held

ops.dequeue() is invoked with the source user DSQ's lock still held on
the consume and move paths (scx_consume_dispatch_q(),
move_task_between_dsqs()). A BPF scheduler which locks the source user
DSQ from ops.dequeue() - e.g. by iterating it with bpf_iter_scx_dsq -
self-deadlocks.

ops.dequeue() can only call the "any" kfuncs and none of them can lock a
builtin DSQ, so the global and bypass paths can't deadlock; however,
all DSQ locks share one lockdep class, so iterating any user DSQ from
ops.dequeue() on those paths trips the recursion check.

Move the invocation after the DSQ unlock on all three paths.
SCX_TASK_IN_CUSTODY is cleared under the lock serializing the transfer
so that the callback is invoked exactly once.

## Which versions are affected by CVE-2026-98865?


## How do I fix CVE-2026-98865?

Apply the vendor's patch.

## Is CVE-2026-98865 being exploited?

There is no known exploitation of CVE-2026-98865 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98865 and fix it if it is affected.

What it is: CVE-2026-98865 is a denial of service vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98865 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98865/ (Markdown: https://insights.sbomify.com/CVE-2026-98865/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98865
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98865
- OSV: https://osv.dev/vulnerability/CVE-2026-98865

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98865/
Summaries are generated and may contain mistakes; the official description above is the record.