GHSA-fg94-h982-f3mm
Suggest an improvement- Source
- https://github.com/advisories/GHSA-fg94-h982-f3mm
- Import Source
- https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-fg94-h982-f3mm/GHSA-fg94-h982-f3mm.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/GHSA-fg94-h982-f3mm
- Aliases
- Downstream
- Published
- 2026-06-17T18:06:06Z
- Modified
- 2026-07-20T21:16:21.515033598Z
- Severity
-
- 9.1 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N CVSS Calculator
- 6.0 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
- Summary
- Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch
- Details
-
Because the hostname huggingface.co was pre-approved as a bare hostname for the WebFetch tool, any path on that domain—including attacker-controlled model repositories—was auto-approved without a permission prompt or being subject to --allowedTools restrictions. An attacker able to inject untrusted content into a Claude Code context could direct it to issue WebFetch requests against attacker-controlled repository files (e.g. /resolve/main/config.json), which HuggingFace counts as downloads server-side, creating a covert out-of-band channel for encoding and exfiltrating data Claude can access such as files, environment variables, or command output. Reliably exploiting this required the ability to add untrusted content into a Claude Code context window. Users on standard Claude Code auto-update have received this fix already; users performing manual updates are advised to update to the latest version.
Thank you to hackerone.com/novee for reporting this issue.
- Database specific
{ "severity": "MODERATE", "github_reviewed_at": "2026-06-17T18:06:06Z", "nvd_published_at": "2026-06-23T18:18:08Z", "cwe_ids": [ "CWE-183", "CWE-200", "CWE-515" ], "github_reviewed": true }- References
Affected packages
npm / @anthropic-ai/claude-code
Package
- Name
- @anthropic-ai/claude-code
- View open source insights on deps.dev
- Purl
- pkg:npm/%40anthropic-ai/claude-code