Path Traversal in Fast-Uri

CVE-2026-6321

fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalized path. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed, with a path that appears confined under an allowed prefix normalizing to a different location. Versions <= 3.1.0 are affected. Update to 3.1.1 or later.

Vulnerability class: Path Traversal (Directory Traversal)

EPSS: 0.006 (48.0th percentile) — read the EPSS interpretation.