{"id":"CVE-2026-110725","aliases":["GHSA-333x-w4r6-6crp"],"url":"https://o3.security/vulnerability/CVE-2026-110725","summary":"fast-uri vulnerable to scheme injection via an unescaped first-segment colon in suffix references","details":"### Impact\n\n`fast-uri`'s `serialize()`, `normalize()`, and `resolve()`, when called with the non-default option `reference: 'suffix'` on a reference that has no authority, emit a relative reference whose first path segment contains a bare colon without escaping it. RFC 3986 section 3.3 requires the first segment of a `path-noscheme` reference not to contain a colon, precisely because a bare colon makes the string reparse as an absolute URI with a scheme. `fast-uri`'s default serialization escapes that colon, but the suffix path does not.\n\nFor example, `normalize('javascript:alert(1)', { reference: 'suffix' })` returns `javascript:alert(1)`, which reparses as a live `javascript:` scheme; `data:` and `vbscript:` behave the same.\n\nApplications that serialize or normalize a relative reference with `reference: 'suffix'` and then treat the result as a URI can turn inert input into a live `javascript:`, `data:`, or `vbscript:` URL (a cross-site scripting vector), and `equal()` can conflate a scheme-bearing reference with a relative one. Exposure is limited to applications that use the non-default `reference: 'suffix'` option.\n\n### Patches\n\nUpgrade to `fast-uri` `2.4.8`, `3.1.9`, or `4.2.3`.\n\n### Workarounds\n\nDo not use the `reference: 'suffix'` option on untrusted input. If suffix output is required, percent-encode a colon in the first path segment of the result before treating it as a URI.","published":"2026-10-20T07:06:29.946Z","modified":"2026-10-24T02:31:00.506987774Z","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/39e6493c1356f30a0084171627eb266786e1620e","label":"fastify/fast-uri@39e6493"},"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-2026-110725.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fast-uri/security/advisories/GHSA-333x-w4r6-6crp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110725"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/39e6493c1356f30a0084171627eb266786e1620e"},{"type":"WEB","url":"https://github.com/fastify/fast-uri/commit/a9b8d67353630aab053cd727cf629023dd018d2b"},{"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":"2026-10-24T02:31:00.506987774Z"}}