Weights & Biases wandb before 0.29.0 fails to validate the file name from server responses in the File.download function, allowing path traversal attacks. Attackers controlling the backend can supply file names with directory traversal sequences to write files outside the intended download directory, potentially enabling code execution through modification of shell startup files or Python import paths.

Weights & Biases wandb versions before 0.29.0 contain a path traversal vulnerability in the File.download function. The library fails to validate file names returned from server responses, allowing attackers who control the backend to supply directory traversal sequences. This can result in files being written outside the intended download directory. The vulnerability could enable remote code execution by overwriting shell startup files or manipulating Python import paths. It affects users of the wandb MLOps/experiment tracking library who connect to untrusted or compromised backends. The issue was identified in wandb/apis/public/files.py and patched in version 0.29.0. A fix was committed and a GitHub issue documents the vulnerability.