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CVE-2026-54316 — Vulnerability in @anthropic-ai/claude-code — CVE...

MEDIUM

Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch

Published June 17, 2026Updated July 20, 2026Source: osv

Summary

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.

Advisory Timeline

  • First published June 17, 2026 (117 days ago).
  • Last revised July 20, 2026 — 33 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

npm
Update @anthropic-ai/claude-code to 2.1.163 or later
npm install @anthropic-ai/claude-code@2.1.163

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: npm (1).

PackageEcosystemAffectedFixed In
@anthropic-ai/claude-code
npm
All versions2.1.163

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.1 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

Frequently Asked Questions

What is CVE-2026-54316?
Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch This vulnerability has been assigned a severity rating of MEDIUM (CVSS score: 9.1/10).
How do I check if my project is affected by CVE-2026-54316?
CVE-2026-54316 affects @anthropic-ai/claude-code. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-54316 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.1

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-fg94-h982-f3mm

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