A deserialization vulnerability exists in Volcengine's verl 3.0.0, specifically in...

Vulnerability 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.

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