Arbitrary file write via unvalidated download filename
Published Sep 15, 2026 · Updated Sep 15, 2026
Path traversal in Weights & Biases wandb before 0.29.0 allows attackers controlling its backend to write outside the download directory. File.download trusts the file name returned by the server and joins traversal sequences to the requested root without containing the resolved path. Control of the configured backend is required; overwritten shell startup files or Python import paths execute attacker content when later loaded.
Summary
What happened
Path traversal in Weights & Biases wandb before 0.29.0 allows attackers controlling its backend to write outside the download directory. File.download trusts the file name returned by the server and joins traversal sequences to the requested root without containing the resolved path. Control of the configured backend is required; overwritten shell startup files or Python import paths execute attacker content when later loaded.
The record
- CVE
- CVE-2026-91771
- Published
- Sep 15, 2026
- Updated
- Sep 15, 2026
- Vendor
- Weights & Biases
- Product
- wandb
- Classifications
- T1546.004
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Sep 15, 2026CVE publishedPublication date reported by the CVE source.
- Sep 15, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.29.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo