Vulnerability details
Vulnerability
Data from Dependency-Track
Affected versions
Score
Description
### 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.