CVE-2026-91771

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Path Traversal in Weights & Biases wandb

Publication date: 2026-09-15

Last updated on: 2026-09-24

Assigner: VulnCheck

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-15

Last Modified

2026-09-24

Generated

2026-10-05

AI Q&A

2026-09-15

EPSS Evaluated

2026-10-04

NVD

CVE-2026-91771

EUVD

EUVD-2026-78247

Affected Vendors & Products

Vendor	Product	Version / Range
weights_and_biases	wandb	to 0.29.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-22	The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

Executive Summary

This vulnerability is a path traversal issue in Weights & Biases (wandb) versions before 0.29.0. The File.download function fails to validate file names from server responses, allowing attackers controlling the backend to supply file names with directory traversal sequences. This enables writing files outside the intended download directory, potentially leading to code execution by modifying shell startup files or Python import paths.

Detection Guidance

To detect this vulnerability, check the installed version of wandb on your system. Run: pip show wandb. If the version is below 0.29.0, the system is vulnerable. Additionally, review file download logs for unusual paths containing directory traversal sequences like ../ or absolute paths.

Impact Analysis

An attacker could exploit this to write malicious files to arbitrary locations on your system. This might allow them to execute arbitrary code by overwriting critical files like shell startup scripts or Python modules. The impact includes potential data theft, system compromise, or further lateral movement within a network.

Compliance Impact

This vulnerability could lead to unauthorized file access or modification, violating data integrity and confidentiality requirements in GDPR and HIPAA. It may result in unauthorized exposure of sensitive data, non-compliance with access controls, and potential breaches of personal or health information protections.

Mitigation Strategies

Immediately update wandb to version 0.29.0 or later. Run: pip install --upgrade wandb. If updating is not possible, restrict network access to the wandb backend to prevent malicious file names from being supplied.

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