CVE-2026-54316: Claude Code Out-of-Band Data Exfiltration via WebFetch

# CVE-2026-54316: Claude Code Out-of-Band Data Exfiltration via WebFetch

https://gcdradar.vercel.app/incidents/cve-2026-54316-claude-code-out-of-band-data-exfiltration-via · AIR-2026-0762 · closed 2026-06-17

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-06-17
- AI role: Attack on AI
- Products: Claude Code
- CVE ids: CVE-2026-54316
- CVSS: 9.1

## Summary

Pre-approval of huggingface.co in Claude Code's WebFetch tool allowed automatic requests to attacker-controlled repositories without permission prompts. This created a covert channel for data exfiltration via server-side download metrics.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-06-23: CVE-2026-54316: Claude Code is an agentic coding tool. (https://nvd.nist.gov/vuln/detail/CVE-2026-54316)
- 2026-06-17: CVE-2026-54316: Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch (https://github.com/advisories/GHSA-fg94-h982-f3mm)

## Sources

- 2026-06-17 GitHub Advisory Database: CVE-2026-54316: Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch https://github.com/advisories/GHSA-fg94-h982-f3mm
- 2026-06-23 NVD: CVE-2026-54316: Claude Code is an agentic coding tool. https://nvd.nist.gov/vuln/detail/CVE-2026-54316

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.