CVE-2026-6321 — fast-uri vulnerable to path traversal via percent-encoded dot segments

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
fast-uri / fast-uri	affected 0 before 3.1.1; unaffected 3.1.1

CWE

CWE-22

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in fast-uri. A remote attacker could exploit this vulnerability by providing a specially crafted Uniform Resource Locator (URL) containing percent-encoded path separators and dot segments. Due to incorrect processing, fast-uri would decode these elements before proper normalization, leading to distinct URLs resolving to the same internal path. This could allow an attacker to bypass security policies that rely on path-based comparisons, potentially gaining unauthorized access to resources.