{"id":"CVE-2026-84292","aliases":["GHSA-qw65-cvwx-89v3"],"url":"https://o3.security/vulnerability/CVE-2026-84292","summary":"fast-uri vulnerable to authority injection via an unvalidated port in serialize","details":"### Impact\n\n`fast-uri` serializes the `port` component of a URI without validating it. When recomposing the authority, `fast-uri` escapes the userinfo and host components but concatenates the port verbatim, so a `port` value that is not a sequence of digits can inject authority delimiters. For example, serializing a component whose `port` is `@127.0.0.1:8124` produces `http://trusted.example:@127.0.0.1:8124/app`, demoting the intended host to userinfo and pointing the authority at an attacker-controlled host. Both `fast-uri` and Node's `URL` read the result back as the attacker's host with no error, so re-validating the built URI does not catch it.\n\nThis affects applications that build URIs from parts and assign untrusted data to the `port` component (for example a fixed host from configuration and a port taken from user input or a service record). The same path is reachable through `serialize()`, `normalize()`, and `equal()` in their object forms. A `port` obtained from `parse()` is always digits and is not affected.\n\n### Patches\n\nThis vulnerability has been patched in fast-uri `4.1.4`, `3.1.7`, and `2.4.6`. `recomposeAuthority` now rejects any port that is not `*DIGIT` per RFC 3986. All users should upgrade.\n\n### Workarounds\n\nIf upgrading is not immediately possible, validate the `port` value against the RFC 3986 grammar (digits only) before passing a component to `serialize()`, `normalize()`, or `equal()`, and reject anything else, for example `if (!/^\\d*$/.test(String(port))) throw new Error('invalid port')`.","published":"2026-09-02T20:09:51.415Z","modified":"2026-10-21T02:30:26.285290914Z","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"fast-uri","fixedVersion":"2.4.6"},{"ecosystem":"npm","name":"fast-uri","fixedVersion":"3.1.7"},{"ecosystem":"npm","name":"fast-uri","fixedVersion":"4.1.4"}],"fix":{"url":"https://github.com/fastify/fast-uri/commit/820e8478dd7da3d09f187bfaf35d50b71f67b8b4","label":"fastify/fast-uri@820e847"},"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-2026-84292.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-qw65-cvwx-89v3"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84292"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/820e8478dd7da3d09f187bfaf35d50b71f67b8b4"},{"type":"PACKAGE","url":"https://github.com/fastify/fast-uri"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v2.4.6"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v3.1.7"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v4.1.4"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:30:26.285290914Z"}}