GHSA-xhq7-xmqj-769h
fast-uri vulnerable to improper path equivalence in relative reference normalization
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### Impact
`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.
For 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.
Applications 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.
### Patches
Upgrade to `fast-uri` `2.4.8`, `3.1.9`, or `4.2.3`.
### Workarounds
Do not normalize a relative reference before resolving it. Resolve it against the absolute base first, then normalize the absolute result.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/fastify/fast-uri/security/advisories/GHSA-xhq7-xmqj-769h
- https://nvd.nist.gov/vuln/detail/CVE-2026-110095
- https://github.com/fastify/fast-uri/commit/048bbd0a252971be86d6579f0dfc87f8de5b9c47
- https://github.com/fastify/fast-uri/commit/52774a5c35df36b0bbe439cd4c12c3dc0e50e3b9
- https://github.com/fastify/fast-uri/commit/7c19f8b97ec51f1f20b4e3d9d5820cb8d5176058
- https://github.com/fastify/fast-uri/commit/9eb8759a9825c046f57f7f695f1944bc39b88abd
- https://github.com/fastify/fast-uri/commit/acc5c5d60c4209571789496e1732468911c7e12a
- https://github.com/fastify/fast-uri/commit/b110a3571c37dfcf9d1c72ce2e2e178c78d1a424
- https://cna.openjsf.org/security-advisories.html
- https://github.com/fastify/fast-uri
- https://github.com/fastify/fast-uri/releases/tag/v2.4.8
- https://github.com/fastify/fast-uri/releases/tag/v3.1.9
- https://github.com/fastify/fast-uri/releases/tag/v4.2.3