{"id":"CVE-2026-110095","aliases":["GHSA-xhq7-xmqj-769h"],"url":"https://o3.security/vulnerability/CVE-2026-110095","summary":"fast-uri vulnerable to improper path equivalence in relative reference normalization","details":"### Impact\n\n`fast-uri`'s `normalize()` and `serialize()` apply RFC 3986 dot-segment removal (`remove_dot_segments`) to the path of a relative-path reference. RFC 3986 section 5.2.4 defines that algorithm only for the merged target path during resolution, not for the reference itself, so applied to the reference it drops leading `..` segments and can turn a document-relative reference into a root-relative one.\n\nFor example, `normalize('a/../b')` returns `/b` and `normalize('../x')` returns `x`, so `resolve(base, normalize(ref))` points at a different resource than `resolve(base, ref)`, and `equal()` treats distinct references as the same.\n\nApplications that normalize attacker-supplied or user-supplied relative references and then resolve them, or use them as cache, deduplication, or authorization keys, can have a reference escape its intended directory and point at a different resource.\n\n### Patches\n\nUpgrade to `fast-uri` `2.4.8`, `3.1.9`, or `4.2.3`.\n\n### Workarounds\n\nDo not normalize a relative reference before resolving it. Resolve it against the absolute base first, then normalize the absolute result.","published":"2026-10-20T06:56:56.456Z","modified":"2026-10-24T02:30:27.180339605Z","cvss":{"score":3.7,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"fast-uri","fixedVersion":"2.4.8"},{"ecosystem":"npm","name":"fast-uri","fixedVersion":"3.1.9"},{"ecosystem":"npm","name":"fast-uri","fixedVersion":"4.2.3"}],"fix":{"url":"https://github.com/fastify/fast-uri/commit/048bbd0a252971be86d6579f0dfc87f8de5b9c47","label":"fastify/fast-uri@048bbd0"},"references":[{"type":"ADVISORY","url":"https://cna.openjsf.org/security-advisories.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/110xxx/CVE-2026-110095.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-xhq7-xmqj-769h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110095"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/048bbd0a252971be86d6579f0dfc87f8de5b9c47"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/52774a5c35df36b0bbe439cd4c12c3dc0e50e3b9"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/7c19f8b97ec51f1f20b4e3d9d5820cb8d5176058"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/9eb8759a9825c046f57f7f695f1944bc39b88abd"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/acc5c5d60c4209571789496e1732468911c7e12a"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/b110a3571c37dfcf9d1c72ce2e2e178c78d1a424"},{"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-24T02:30:27.180339605Z"}}