# CVE-2025-37940: ftrace: Add cond_resched() to ftrace_graph_set_hash()

> A missing scheduling call in the Linux kernel ftrace subsystem can cause softlockups and system unresponsiveness when tracing many functions.

- **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:** 20 May 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-37940, DEBIAN-CVE-2025-37940, GHSA-69hw-3r8x-9jf6, ROOT-OS-DEBIAN-11-CVE-2025-37940, ROOT-OS-UBUNTU-2204-CVE-2025-37940, ROOT-OS-UBUNTU-2404-CVE-2025-37940, UBUNTU-CVE-2025-37940

## What is CVE-2025-37940?

CVE-2025-37940 is a medium-severity denial of service 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:

ftrace: Add cond_resched() to ftrace_graph_set_hash()

When the kernel contains a large number of functions that can be traced,
the loop in ftrace_graph_set_hash() may take a lot of time to execute.
This may trigger the softlockup watchdog.

Add cond_resched() within the loop to allow the kernel to remain
responsive even when processing a large number of functions.

This matches the cond_resched() that is used in other locations of the
code that iterates over all functions that can be traced.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-37940?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2025-37940?

Apply the vendor's patch.

## Is CVE-2025-37940 being exploited?

There is no known exploitation of CVE-2025-37940 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-2025-37940 and fix it if it is affected.

What it is: CVE-2025-37940 is a medium-severity denial of service 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-2025-37940 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-2025-37940/ (Markdown: https://insights.sbomify.com/CVE-2025-37940/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37940
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37940
- OSV: https://osv.dev/vulnerability/CVE-2025-37940

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37940/
Summaries are generated and may contain mistakes; the official description above is the record.