Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch_CVE-2026-54316

{
    "lastseen": "",
    "description": "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\u2014including attacker-controlled model repositories\u2014was 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.",
    "published": "2026-06-23T17:06:16.184Z",
    "modified": "2026-06-23T17:37:38.468Z",
    "type": "cve",
    "title": "Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch",
    "source": "GitHub_M",
    "references": "https://github.com/anthropics/claude-code/security/advisories/GHSA-fg94-h982-f3mm",
    "id": "CVE-2026-54316",
    "bulletinFamily": "",
    "cwe": [
        "CWE-183",
        "CWE-200",
        "CWE-515"
    ],
    "cvelist": null,
    "sourceData": "anthropics claude-code >= 0.2.54, < 2.1.163",
    "sourceHref": "",
    "cvss": {
        "score": 6,
        "severity": "MEDIUM",
        "vector": "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "claude-code",
    "version": ">= 0.2.54, < 2.1.163",
    "vendor": "anthropics",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}