# CVE-2025-4287: PyTorch nccl.py torch.cuda.nccl.reduce denial of service

> A local attacker can cause a denial of service in PyTorch via the torch.cuda.nccl.reduce function, requiring a patch to mitigate.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **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:** No
- **Published:** 5 May 2025
- **Updated:** 6 May 2025
- **Also known as:** DEBIAN-CVE-2025-4287, ECHO-3734-1b40-b231, GHSA-vw34-v45x-2c97, UBUNTU-CVE-2025-4287

## What is CVE-2025-4287?

CVE-2025-4287 is a medium-severity denial of service vulnerability in PyTorch, published on 5 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was found in PyTorch 2.6.0+cu124. It has been rated as problematic. Affected by this issue is the function torch.cuda.nccl.reduce of the file torch/cuda/nccl.py. The manipulation leads to denial of service. It is possible to launch the attack on the local host. The exploit has been disclosed to the public and may be used. The patch is identified as 5827d2061dcb4acd05ac5f8e65d8693a481ba0f5. It is recommended to apply a patch to fix this issue.

Weakness: CWE-404 (Improper Resource Shutdown or Release)

## Which versions are affected by CVE-2025-4287?


## How do I fix CVE-2025-4287?

No fix has been published for CVE-2025-4287 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-4287 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-4287 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-4287 and fix it if it is affected.

What it is: CVE-2025-4287 is a medium-severity denial of service vulnerability in PyTorch, published on 5 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-4287 exists.

Affected product: PyTorch. 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-2025-4287/ (Markdown: https://insights.sbomify.com/CVE-2025-4287/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-4287
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-4287
- OSV: https://osv.dev/vulnerability/CVE-2025-4287

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-4287/
Summaries are generated and may contain mistakes; the official description above is the record.