# CVE-2026-89519: sched_ext: Replace SCX_RQ_BAL_KEEP with a dispatch verdict return

> A race condition in the Linux kernel's sched_ext scheduler can cause a stale flag to keep a dequeued task running, potentially leading to system instability or denial of service.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-89519, GHSA-4vmj-w324-pvrj, UBUNTU-CVE-2026-89519

## What is CVE-2026-89519?

CVE-2026-89519 is a vulnerability in Linux, published on 11 Sep 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: Replace SCX_RQ_BAL_KEEP with a dispatch verdict return

SCX_RQ_BAL_KEEP tells the pick to keep running the previous task, a leftover
from when balancing and picking were separate operations. An rq-level flag
only works while dispatches and picks pair up one to one, which core
scheduling breaks: selections interleave through dispatch's lock drops and a
pick can consume a stale flag, keeping a task that has since been dequeued.
Fixing core scheduling support requires the decision to travel with the
dispatch that made it. Make scx_dispatch_sched() and balance_one() return an
explicit verdict instead and drop the flag's plumbing from the tools autogen
enum headers.

Also factor the pick-side invocation, its follow-up queueing and the
post-dispatch checks out of do_pick_task_scx() into dispatch_pick(). No
functional changes intended.

v2: Drop the SCX_RQ_BAL_KEEP plumbing from the tools autogen enum headers
    as well (Andrea).

## Which versions are affected by CVE-2026-89519?


## How do I fix CVE-2026-89519?

Apply the vendor's patch.

## Is CVE-2026-89519 being exploited?

There is no known exploitation of CVE-2026-89519 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89519 and fix it if it is affected.

What it is: CVE-2026-89519 is a vulnerability in Linux, published on 11 Sep 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-2026-89519 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-2026-89519/ (Markdown: https://insights.sbomify.com/CVE-2026-89519/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89519
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89519
- OSV: https://osv.dev/vulnerability/CVE-2026-89519

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89519/
Summaries are generated and may contain mistakes; the official description above is the record.