# CVE-2026-99104: sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-99104, GHSA-73px-7g6q-p2m6, UBUNTU-CVE-2026-99104

## What is CVE-2026-99104?

CVE-2026-99104 is a vulnerability in Linux, published on 28 Oct 2026. 

### Official description

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

sched_ext: Fix the bypass dispatch claim for schedulers bypassed by an ancestor

scx_bypass() claims bypass dispatch when the scheduler's depth goes from
zero to one and releases it when the depth returns to zero, but propagates
only the depth to the descendants, not the claim. A descendant that starts
bypassing with its ancestor never claims, and one whose own bypass ends
under the ancestor's keeps its claim, as its depth does not return to zero.

A sub-scheduler enable whose bypass ends under a PM suspend thus leaks its
claim: the parent keeps hosting bypass dispatch and the sub-scheduler's next
bypass trips the WARN_ON_ONCE() on the claim. A sub-scheduler disable that
starts under a PM suspend has no claim, so once the resume lifts the root's
bypass its tasks sit on the parent's bypass DSQs with nobody consuming them.

Claim for every descendant whose depth goes from zero to one in the
propagation and release every scheduler in the subtree whose depth returned
to zero once the tasks have moved out of the bypass DSQs. A parent that is
bypassing itself when a descendant claims consumes only its own bypass DSQs,
empty until it leaves bypass and becomes the host.

## Which versions are affected by CVE-2026-99104?


## How do I fix CVE-2026-99104?

Upgrade to a fixed version.

## Is CVE-2026-99104 being exploited?

There is no known exploitation of CVE-2026-99104 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99104 and fix it if it is affected.

What it is: CVE-2026-99104 is a vulnerability in Linux, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99104 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-2026-99104/ (Markdown: https://insights.sbomify.com/CVE-2026-99104/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99104
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99104
- OSV: https://osv.dev/vulnerability/CVE-2026-99104

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99104/
Summaries are generated and may contain mistakes; the official description above is the record.