GitHub Advisoryadvisory · npm

GHSA-q3j6-qgpj-74h6 fast-uri vulnerable to path traversal via percent-encoded dot segments

HIGH Published 2026-05-08 Modified 2026-08-20 Official page ↗
Aliases
CVE-2026-6321
Ecosystem
npm
Packages
fast-uri
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weaknesses
CWE-22
Reviewed
2026-05-08

Affected packages

• npm fast-uri: >= 3.0.0, < 3.1.1 → fixed in 3.1.1 • npm fast-uri: < 2.4.1 → fixed in 2.4.1

Description

Impact `fast-uri` v3.1.0 and earlier decodes percent-encoded path separators (`%2F`) and dot segments (`%2E`) before applying dot-segment removal in `normalize()` and `equal()`. This makes encoded path data behave like real `/` and `..`, so distinct URIs collapse onto the same normalized path. For example, `http://example.com/public/%2e%2e/admin` normalizes to `http://example.com/admin`, and `equal()` considers them the same URI. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed. A path that looks confined under an allowed prefix can normalize to a different location. Patches Upgrade to `fast-uri` >= 3.1.1, or if you are in the v2.x release line, v2.4.1 Workarounds None. Upgrade to the patched version.

Related

Alias · CVE (1)

  • CVE-2026-6321 fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal()… vulnerability

Weakness · CWE (1)

  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory weakness

References