Claude Code — Data Exfiltration (CVE-2026-54316)
Date: 2026-06
Affected: anthropic/claude_code
Attack vector: data-exfiltration
Category: vulnerability-disclosure
Severity: Critical
CVE: CVE-2026-54316
CWE: CWE-183
CWE-200
CWE-515
CVSS: 9.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)

Claude Code is an agentic coding tool. From 0.2.54 until 2.1.163, 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. This vulnerability is fixed in 2.1.163.


Mitigations:

Architectural layers (MAESTRO):