Interpretation Conflict Affecting fast-uri package, versions >=2.4.2 <2.4.5>=3.1.3 <3.1.6>=4.0.1 <4.1.3
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-FASTURI-19256867
- published25 Aug 2026
- disclosed24 Aug 2026
- creditbaeseungwon1010
Introduced: 24 Aug 2026
NewCVE-2026-75931 (opens in a new tab)How to fix?
Upgrade fast-uri to version 2.4.5, 3.1.6, 4.1.3 or higher.
Overview
fast-uri is a Dependency-free RFC 3986 URI toolbox
Affected versions of this package are vulnerable to Interpretation Conflict in resolve() through the resolve() process in index.js. An attacker can make an application resolve a scheme-relative reference such as //host/ against a scheme-bearing base and receive a host string that does not match the host produced when the result is parsed again. This lets policy checks or routing decisions operate on one host while the resolved URI actually points at another, which can bypass host allowlists and send the user to an unexpected destination.
Workarounds
- Resolve scheme-relative references against a base URI that already includes a scheme before any host-policy or origin check, so the host is evaluated in its final scheme context and cannot be checked under one interpretation and used under another.