# CVE-2026-91771: Weights & Biases wandb before 0.29.0 Path Traversal via File Download

> Attackers controlling the backend can exploit path traversal in wandb to write files outside the download directory, potentially enabling code execution.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-h5x7-chgg-fqcc

## What is CVE-2026-91771?

CVE-2026-91771 is a high-severity path traversal vulnerability in wandb, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-91771?


## How do I fix CVE-2026-91771?

No fix has been published for CVE-2026-91771 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-91771 being exploited?

There is no known exploitation of CVE-2026-91771 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91771 and fix it if it is affected.

What it is: CVE-2026-91771 is a high-severity path traversal vulnerability in wandb, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-91771 in the wild and no public exploit code.

Affected product: wandb. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-91771/ (Markdown: https://insights.sbomify.com/CVE-2026-91771/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91771
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91771
- OSV: https://osv.dev/vulnerability/CVE-2026-91771

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91771/
Summaries are generated and may contain mistakes; the official description above is the record.