# CVE-2022-50668: ext4: fix deadlock due to mbcache entry corruption

> A race condition in the Linux kernel ext4 filesystem can cause an infinite loop and deadlock, leading to a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2022-50668, GHSA-22wc-8hcq-634h, UBUNTU-CVE-2022-50668

## What is CVE-2022-50668?

CVE-2022-50668 is a high-severity vulnerability in Linux, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

ext4: fix deadlock due to mbcache entry corruption

When manipulating xattr blocks, we can deadlock infinitely looping
inside ext4_xattr_block_set() where we constantly keep finding xattr
block for reuse in mbcache but we are unable to reuse it because its
reference count is too big. This happens because cache entry for the
xattr block is marked as reusable (e_reusable set) although its
reference count is too big. When this inconsistency happens, this
inconsistent state is kept indefinitely and so ext4_xattr_block_set()
keeps retrying indefinitely.

The inconsistent state is caused by non-atomic update of e_reusable bit.
e_reusable is part of a bitfield and e_reusable update can race with
update of e_referenced bit in the same bitfield resulting in loss of one
of the updates. Fix the problem by using atomic bitops instead.

This bug has been around for many years, but it became *much* easier
to hit after commit 65f8b80053a1 ("ext4: fix race when reusing xattr
blocks").

## Which versions are affected by CVE-2022-50668?


## How do I fix CVE-2022-50668?

Apply the vendor's patch.

## Is CVE-2022-50668 being exploited?

There is no known exploitation of CVE-2022-50668 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50668 and fix it if it is affected.

What it is: CVE-2022-50668 is a high-severity vulnerability in Linux, published on 9 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-50668 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-2022-50668/ (Markdown: https://insights.sbomify.com/CVE-2022-50668/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50668
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50668
- OSV: https://osv.dev/vulnerability/CVE-2022-50668

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50668/
Summaries are generated and may contain mistakes; the official description above is the record.