{"id":"CVE-2026-54316","aliases":["GHSA-fg94-h982-f3mm"],"url":"https://o3.security/vulnerability/CVE-2026-54316","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.","published":"2026-06-23T17:06:16.184Z","modified":"2026-08-12T03:51:38.110243995Z","cvss":null,"epss":{"score":0.00466,"percentile":0.38631,"asOf":"2026-09-02"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@anthropic-ai/claude-code","fixedVersion":"2.1.163"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54316.json"},{"type":"ADVISORY","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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:38.110243995Z"}}