# CVE-2026-93220: sched_ext: Keep kick_sync waiting on the rq's own CPU

> A race condition in the Linux kernel's sched_ext scheduler can cause a deadlock, leading to 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:** 24 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-93220, GHSA-mp4r-853f-vhwr, UBUNTU-CVE-2026-93220

## What is CVE-2026-93220?

CVE-2026-93220 is a vulnerability in Linux, published on 24 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: Keep kick_sync waiting on the rq's own CPU

kick_sync_wait_bal_cb() assumes it runs on the rq's CPU from the
__schedule() tail: the snapshots it compares against live in that CPU's
percpu area and the busy-wait runs with the rq lock dropped and IRQs
enabled.

However, dispatch can now drop the rq lock while the callback sits queued,
and rq lock takers in that window (the sched class change paths, the scx
task iterator) flush pending balance callbacks on release, running the
callback on a foreign CPU. Such a run compares against unrelated snapshots
and can deadlock when the executing CPU is itself a wait target.

Bail on a foreign CPU and leave the wait state alone. The wait only observes
progress that the resched kicks already guarantee and the rq's next wait
picks up the stale cpus_to_sync bits.

## Which versions are affected by CVE-2026-93220?


## How do I fix CVE-2026-93220?

Apply the vendor's patch.

## Is CVE-2026-93220 being exploited?

There is no known exploitation of CVE-2026-93220 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93220 and fix it if it is affected.

What it is: CVE-2026-93220 is a vulnerability in Linux, published on 24 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-2026-93220 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-2026-93220/ (Markdown: https://insights.sbomify.com/CVE-2026-93220/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93220
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93220
- OSV: https://osv.dev/vulnerability/CVE-2026-93220

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93220/
Summaries are generated and may contain mistakes; the official description above is the record.