# CVE-2025-38539: tracing: Add down_write(trace_event_sem) when adding trace event

> Concurrent module loading can corrupt trace event lists, causing a kernel crash and denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 16 Aug 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-66371, AZL-73572, BELL-CVE-2025-38539, DEBIAN-CVE-2025-38539, GHSA-jgp9-rwc2-m645, ROOT-OS-DEBIAN-11-CVE-2025-38539, ROOT-OS-DEBIAN-12-CVE-2025-38539, ROOT-OS-DEBIAN-13-CVE-2025-38539, ROOT-OS-UBUNTU-2204-CVE-2025-38539, ROOT-OS-UBUNTU-2404-CVE-2025-38539, UBUNTU-CVE-2025-38539

## What is CVE-2025-38539?

CVE-2025-38539 is a high-severity vulnerability in Debian Debian Linux, published on 16 Aug 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: Add down_write(trace_event_sem) when adding trace event

When a module is loaded, it adds trace events defined by the module. It
may also need to modify the modules trace printk formats to replace enum
names with their values.

If two modules are loaded at the same time, the adding of the event to the
ftrace_events list can corrupt the walking of the list in the code that is
modifying the printk format strings and crash the kernel.

The addition of the event should take the trace_event_sem for write while
it adds the new event.

Also add a lockdep_assert_held() on that semaphore in
__trace_add_event_dirs() as it iterates the list.

## Which versions are affected by CVE-2025-38539?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-38539?

Apply the vendor's patch.

## Is CVE-2025-38539 being exploited?

There is no known exploitation of CVE-2025-38539 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-2025-38539 and fix it if it is affected.

What it is: CVE-2025-38539 is a high-severity vulnerability in Debian Debian Linux, published on 16 Aug 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-2025-38539 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-2025-38539/ (Markdown: https://insights.sbomify.com/CVE-2025-38539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38539
- OSV: https://osv.dev/vulnerability/CVE-2025-38539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38539/
Summaries are generated and may contain mistakes; the official description above is the record.