# CVE-2025-37938: tracing: Verify event formats that have "%*p.."

> A missing verification in Linux kernel trace event formats allows reading freed memory, potentially causing a kernel crash via null dereference.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:** 20 May 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-72829, BELL-CVE-2025-37938, DEBIAN-CVE-2025-37938, GHSA-r878-fwjf-3cg7, ROOT-OS-UBUNTU-2204-CVE-2025-37938, ROOT-OS-UBUNTU-2404-CVE-2025-37938, UBUNTU-CVE-2025-37938

## What is CVE-2025-37938?

CVE-2025-37938 is a high-severity vulnerability in Debian Debian Linux, published on 20 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:

tracing: Verify event formats that have "%*p.."

The trace event verifier checks the formats of trace events to make sure
that they do not point at memory that is not in the trace event itself or
in data that will never be freed. If an event references data that was
allocated when the event triggered and that same data is freed before the
event is read, then the kernel can crash by reading freed memory.

The verifier runs at boot up (or module load) and scans the print formats
of the events and checks their arguments to make sure that dereferenced
pointers are safe. If the format uses "%*p.." the verifier will ignore it,
and that could be dangerous. Cover this case as well.

Also add to the sample code a use case of "%*pbl".

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-37938?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-37938?

Apply the vendor's patch.

## Is CVE-2025-37938 being exploited?

There is no known exploitation of CVE-2025-37938 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-37938 and fix it if it is affected.

What it is: CVE-2025-37938 is a high-severity vulnerability in Debian Debian Linux, published on 20 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-2025-37938 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-2025-37938/ (Markdown: https://insights.sbomify.com/CVE-2025-37938/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37938
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37938
- OSV: https://osv.dev/vulnerability/CVE-2025-37938

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37938/
Summaries are generated and may contain mistakes; the official description above is the record.