CVE-2026-91771: Weights & Biases wandb before 0.29.0 Path Traversal via File Download
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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Weights & Biases wandbto a version that resolves this vulnerability.Fixed in 0.29.0Patch Weights & Biases wandb before 0.29.0 Path Traversal via File Download
Event History
Frequently Asked Questions
Who can exploit this issue in practice?
An attacker must control the backend that supplies file-download responses to the wandb client. The vulnerable client then uses an attacker-controlled file name when downloading.
Are default wandb installations affected?
The issue affects wandb versions before 0.29.0 when the File.download function processes a malicious file name from a backend response. The provided information does not identify any configuration setting required to enable or disable the vulnerable behavior.
What can an attacker do with a successful exploit?
A malicious backend can use directory-traversal sequences to write files outside the intended download directory. This may enable code execution if the attacker can overwrite shell startup files or files in Python import paths.
What is the available remediation?
Upgrade Weights & Biases wandb to version 0.29.0 or later. This version includes the referenced fix for validation of downloaded file names.