{"id":"GHSA-fg94-h982-f3mm","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.\n\nThank you to hackerone.com/novee for reporting this issue.","aliases":["CVE-2026-54316"],"modified":"2026-07-20T21:15:27.462388438Z","published":"2026-06-17T18:06:06Z","database_specific":{"cwe_ids":["CWE-183","CWE-200","CWE-515"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-06-17T18:06:06Z","nvd_published_at":"2026-06-23T18:18:08Z"},"references":[{"type":"WEB","url":"https://github.com/anthropics/claude-code/security/advisories/GHSA-fg94-h982-f3mm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54316"},{"type":"PACKAGE","url":"https://github.com/anthropics/claude-code"}],"affected":[{"package":{"name":"@anthropic-ai/claude-code","ecosystem":"npm","purl":"pkg:npm/%40anthropic-ai/claude-code"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.2.54"},{"fixed":"2.1.163"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-fg94-h982-f3mm/GHSA-fg94-h982-f3mm.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"CVSS_V4","score":"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"}]}