# CVE-2025-37808: crypto: null - Use spin lock instead of mutex

> A race condition in the Linux kernel crypto null algorithm can cause a crash when freed in softirq context, requiring a patch to replace mutexes with spin locks.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 8 May 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-37808, DEBIAN-CVE-2025-37808, GHSA-hf6g-cq6h-j3vg, ROOT-OS-DEBIAN-12-CVE-2025-37808, ROOT-OS-UBUNTU-2204-CVE-2025-37808, ROOT-OS-UBUNTU-2404-CVE-2025-37808, UBUNTU-CVE-2025-37808

## What is CVE-2025-37808?

CVE-2025-37808 is a medium-severity vulnerability in Debian Debian Linux, published on 8 May 2025. 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:

crypto: null - Use spin lock instead of mutex

As the null algorithm may be freed in softirq context through
af_alg, use spin locks instead of mutexes to protect the default
null algorithm.

## Which versions are affected by CVE-2025-37808?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-37808?

Apply the vendor's patch.

## Is CVE-2025-37808 being exploited?

There is no known exploitation of CVE-2025-37808 in the wild and no public exploit code.

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## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-37808 and fix it if it is affected.

What it is: CVE-2025-37808 is a medium-severity vulnerability in Debian Debian Linux, published on 8 May 2025. 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-2025-37808 in the wild and no public exploit code.

Affected product: Debian Debian 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-2025-37808/ (Markdown: https://insights.sbomify.com/CVE-2025-37808/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37808
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37808
- OSV: https://osv.dev/vulnerability/CVE-2025-37808

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37808/
Summaries are generated and may contain mistakes; the official description above is the record.