{"id":"CVE-2026-84394","summary":"fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority","details":"fast-uri accepts a host that contains an unbalanced or misplaced authority bracket without reporting an error. A host that starts with an opening bracket but does not end with a closing bracket is neither validated as an IP literal nor canonicalized as a domain name, so parse() returns it as the host with error undefined, while Node's URL and the HTTP clients built on it resolve the same string to a different host. An application that reads the parsed host to make a host decision, such as an SSRF denylist, a redirect allowlist, or proxy routing, and then passes the original URL to an HTTP client evaluates its policy against a string that is not the host the request reaches. The same host is carried through normalize, equal, and resolve. This affects fast-uri versions 2.4.5, 3.1.6, and 4.1.3, and is fixed in 2.4.6, 3.1.7, and 4.1.4, where parse() reports a malformed host for any host that contains a bracket but is not a valid IPv6 literal.","aliases":["GHSA-58mr-gqgx-xq4g"],"modified":"2026-09-06T03:47:03.782450138Z","published":"2026-09-02T20:25:35.399Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84394.json","unresolved_ranges":[{"extracted_events":[{"introduced":"2.4.5"},{"fixed":"2.4.6"},{"introduced":"3.1.6"},{"fixed":"3.1.7"},{"introduced":"4.1.3"},{"fixed":"4.1.4"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"openjs","cwe_ids":["CWE-436"]},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84394.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-58mr-gqgx-xq4g"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84394"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/fastify/fast-uri","events":[{"introduced":"21e274eb54bc738748f66746f4ec1c1e4f919413"},{"last_affected":"4e99790cadffc4b4fdaef9912cb503b328505be0"}],"database_specific":{"source":"CPE_STRING","cpe":["cpe:2.3:a:openjsf:fast-uri:2.4.5:*:*:*:*:node.js:*:*","cpe:2.3:a:openjsf:fast-uri:3.1.6:*:*:*:*:node.js:*:*","cpe:2.3:a:openjsf:fast-uri:4.1.3:*:*:*:*:node.js:*:*"],"extracted_events":[{"introduced":"2.4.5"},{"last_affected":"2.4.5"},{"introduced":"3.1.6"},{"last_affected":"3.1.6"},{"introduced":"4.1.3"},{"last_affected":"4.1.3"}]}}],"versions":["2.4.5","3.1.6","4.1.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84394.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:N/I:H/A:N"}]}