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GHSA-q3j6-qgpj-74h6

fast-uri vulnerable to path traversal via percent-encoded dot segments

Source: GitHub Advisory Database (reviewed) High CVE-2026-6321

Packages

EcosystemPackageAffectedFixed in
npm fast-uri >= 3.0.0, < 3.1.1 3.1.1
npm fast-uri < 2.4.1 2.4.1

Details

As written in the advisory (Markdown source, shown as plain text).

### 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.

References

External links from the advisory. They lead to third-party sites.