{"id":"GHSA-wjr9-j795-jxcr","summary":"fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization","details":"### Impact\n\n`fast-uri` versions `\u003e= 2.4.2, \u003c= 2.4.7`, `\u003e= 3.1.3, \u003c= 3.1.8`, and `\u003e= 4.0.1, \u003c= 4.2.2` can silently rewrite the host of an HTTP-family URL (`http`, `https`, `ws`, `wss`, or any scheme with `domainHost: true`). For those schemes `canonicalizeHost()` passes the parsed host to the WHATWG `URL` parser and adopts its `.hostname` without checking that the parser read the whole input as a host. RFC 3986 permits `@` inside the host group and the WHATWG parser strips TAB, LF, and CR, so the authority `fast-uri` reports is rewritten by that second parser with no `error` set: data before an `@` is dropped and whitespace is removed.\n\nFor example, `fast-uri` parses `http://a@b@evil.example/` to host `evil.example` (dropping the `b` segment), and a host containing a raw TAB, CR, or LF has those characters stripped. `equal()` then treats a whitespace-smuggled host as the same as the clean one, and `resolve()` rewrites the authority the same way.\n\nApplications that use `fast-uri` to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) on one representation, such as the raw input, see a policy/use desync: the canonical host `fast-uri` returns differs from what was checked, and traffic can be steered to an unintended destination.\n\n### Patches\n\nUpgrade to `fast-uri` `2.4.8`, `3.1.9`, or `4.2.3`.\n\n### Workarounds\n\nReject URIs whose authority contains more than one `@`, or contains TAB, CR, or LF, before calling `fast-uri`. Alternatively, treat any non-empty `parse(x).error` as fatal, and compare hosts only from the same `parse()` result.","aliases":["CVE-2026-110180"],"modified":"2026-10-23T21:45:04.892054666Z","published":"2026-10-23T21:37:59Z","database_specific":{"github_reviewed_at":"2026-10-23T21:37:59Z","nvd_published_at":"2026-10-20T07:17:08Z","cwe_ids":["CWE-20","CWE-436"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-wjr9-j795-jxcr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110180"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/58c183d0b168ad87f98773266444ce1f6375803a"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/ddfc6a51122dfce0365655f04479fc3adb7f6b3c"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/f6d46dfeab025d0c440485f4ae29fa4f14707646"},{"type":"WEB","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"PACKAGE","url":"https://github.com/fastify/fast-uri"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v2.4.8"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v3.1.9"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/releases/tag/v4.2.3"}],"affected":[{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.4.2"},{"fixed":"2.4.8"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-wjr9-j795-jxcr/GHSA-wjr9-j795-jxcr.json"}},{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.1.3"},{"fixed":"3.1.9"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-wjr9-j795-jxcr/GHSA-wjr9-j795-jxcr.json"}},{"package":{"name":"fast-uri","ecosystem":"npm","purl":"pkg:npm/fast-uri"},"ranges":[{"type":"SEMVER","events":[{"introduced":"4.0.1"},{"fixed":"4.2.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-wjr9-j795-jxcr/GHSA-wjr9-j795-jxcr.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"}]}