{"id":"GHSA-fph4-wmhf-6fwf","revision":"5c4653ed8f3f4b4aa61353555fc22373","records":[{"revision":"5c4653ed8f3f4b4aa61353555fc22373","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-fph4-wmhf-6fwf","aliases":["CVE-2026-75899"],"title":"fast-uri vulnerable to server-side request forgery via repeated hostname percent-decoding","description":"### Impact\n\n`fast-uri` decodes a hostname's percent escapes twice in a single `normalize()` or `resolve()` call: once during parsing and again during authority recomposition. A nested percent-encoded host therefore survives the first decode and is turned into a live destination by the second, so `normalize('http://%256c%256f%2563%2561%256c%2568%256f%2573%2574/')` returns `http://localhost/`. Applications that normalize or resolve an untrusted URI before an SSRF check, redirect validation, or host allowlist can be steered to a different destination, including internal addresses such as loopback or a cloud metadata endpoint, than the encoded input appeared to contain. This is an incomplete-fix variant of CVE-2026-6322, whose encoded-authority-delimiter fix introduced the second decode.\n\n### Patches\n\nFixed in `fast-uri` 2.4.5, 3.1.6, and 4.1.3.\n\n### Workarounds\n\nReject untrusted URIs whose host component contains an encoded percent sign (`%25`) before passing them to `normalize()` or `resolve()`.","state":0,"publishedAt":"2026-09-02T15:42:39+00:00","modifiedAt":"2026-09-10T03:50:54.42084+00:00","affected":[{"ecosystem":"npm","name":"fast-uri","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"2.4.1"},{"kind":"fixed","version":"2.4.5"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"fast-uri","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"3.1.2"},{"kind":"fixed","version":"3.1.6"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"npm","name":"fast-uri","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"4.0.0"},{"kind":"fixed","version":"4.1.3"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/fastify/fast-uri/security/advisories/GHSA-fph4-wmhf-6fwf","https://nvd.nist.gov/vuln/detail/CVE-2026-75899","https://github.com/fastify/fast-uri/commit/2642290672e7211c990aaed3749c2ce667d0af4f","https://github.com/fastify/fast-uri/commit/8c15dbe94ec50bb8e595791ebb42c35cef0fd304","https://github.com/fastify/fast-uri/commit/ae92a4c5d8c4b6c9e447f048d5fcbde7eebd5514","https://cna.openjsf.org/security-advisories.html","https://github.com/fastify/fast-uri","https://github.com/fastify/fast-uri/releases/tag/v2.4.5","https://github.com/fastify/fast-uri/releases/tag/v3.1.6","https://github.com/fastify/fast-uri/releases/tag/v4.1.3"],"sourceUrl":"https://github.com/advisories/GHSA-fph4-wmhf-6fwf","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-fph4-wmhf-6fwf","identifiers":["GHSA-fph4-wmhf-6fwf","CVE-2026-75899"]},"retained":false,"historicalAffected":[]}],"coverage":[]}