Encoding Error Affecting fast-uri package, versions <2.4.8>=3.0.0 <3.1.9>=4.0.0 <4.2.3
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-21279303
- published20 Oct 2026
- disclosed20 Oct 2026
- creditzekth
Introduced: 20 Oct 2026
NewCVE-2026-110306 (opens in a new tab)How to fix?
Upgrade fast-uri to version 2.4.8, 3.1.9, 4.2.3 or higher.
Overview
fast-uri is a Dependency-free RFC 3986 URI toolbox
Affected versions of this package are vulnerable to Encoding Error via the decodeValidScheme function, which decoded percent-encoded URI schemes using the deprecated unescape() global (including the JavaScript-only %uXXXX form) before validating them. An attacker can supply a percent-encoded scheme such as %6Aavascript:alert(1) or %u006Aavascript:alert(1), causing normalize() to return a live javascript: URI, resolve() to produce a javascript: URL, and equal() to treat the encoded form as equivalent to the decoded scheme. This enables scheme-confusion attacks, most notably cross-site scripting when the resulting URI is used in a browser navigation or href context.