# CVE-2026-74593: sched_ext: Take cgroup_lock() first in scx_cgroup_lock()

> A race condition in the Linux kernel's sched_ext subsystem can cause a deadlock, leading to denial of service when specific cgroup operations are performed concurrently.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Aug 2026
- **Updated:** 23 Aug 2026
- **Also known as:** BELL-CVE-2026-74593, DEBIAN-CVE-2026-74593, GHSA-jp6g-jm55-gwj8, UBUNTU-CVE-2026-74593

## What is CVE-2026-74593?

CVE-2026-74593 is a vulnerability in Linux, published on 22 Aug 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: Take cgroup_lock() first in scx_cgroup_lock()

scx_cgroup_lock() write-locks scx_cgroup_ops_rwsem and then takes
cgroup_lock(), which can deadlock through kernfs:

  scx enable/disable         cgroup rmdir           cpu.weight write
  ------------------         ------------           ----------------
                             cgroup_lock()
  percpu_down_write(rwsem)
  cgroup_lock()
                                                    kernfs_get_active()
                                                    percpu_down_read(rwsem)
                             kernfs_drain()

The enable path waits for the rmdir to release cgroup_mutex. The rmdir,
deactivating the cpu controller's files, waits in kernfs_drain() for the
write's active reference. The write, in scx_group_set_weight(), waits for
the rwsem behind the pending writer.

Take cgroup_lock() first. The set_* paths take no cgroup locks inside the
read side, so a pending write-lock then only waits for read sections that
always run to completion, and no dependency from the rwsem back to
cgroup_mutex remains.

## Which versions are affected by CVE-2026-74593?


## How do I fix CVE-2026-74593?

Apply the vendor's patch.

## Is CVE-2026-74593 being exploited?

There is no known exploitation of CVE-2026-74593 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74593 and fix it if it is affected.

What it is: CVE-2026-74593 is a vulnerability in Linux, published on 22 Aug 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-2026-74593 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-2026-74593/ (Markdown: https://insights.sbomify.com/CVE-2026-74593/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74593
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74593
- OSV: https://osv.dev/vulnerability/CVE-2026-74593

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74593/
Summaries are generated and may contain mistakes; the official description above is the record.