Path Traversal in Weights & Biases wandb

Weights & Biases wandb versions prior to 0.29.0 contain a high-severity path traversal vulnerability in the File.download function. The library fails to validate filenames returned by server responses, allowing an attacker who controls the backend infrastructure to inject directory traversal sequences. By successfully manipulating the file path, the attacker can force the client-side wandb process to write files outside of the intended download directory. This creates a significant security risk, as the attacker may be able to achieve Remote Code Execution (RCE) by overwriting critical system files, such as shell configuration files (e.g., .bashrc, .zshrc) or files within Python site-packages that are loaded at runtime.

Impact

Successful exploitation allows an attacker to achieve arbitrary file writes on the host system. Depending on the environment, this can result in total system compromise, exfiltration of sensitive information, or the execution of malicious code under the context of the user running the wandb library. This vulnerability affects any data science or machine learning pipeline utilizing vulnerable versions of wandb to pull artifacts from a backend server.

Recommendation

• Upgrade the wandb library to version 0.29.0 or later immediately to include path validation in the File.download function.
• Restrict the use of untrusted or unverified backend servers for downloading artifacts via wandb.
• Monitor local file system activity for unexpected file writes originating from Python interpreter processes.