CVE-2026-75899High· 7.5▾ Twilightfast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested per…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0 · exploitation 0
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Exploit-prediction probability, daily snapshots since Sep 2.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.2%
0.2% → 0.4%
Last analysed / modified upstream
fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network destination such as a loopback hostname or address. For example, a doubly encoded host that spells out a loopback name decodes to that live host in one operation, which contradicts RFC 3986 section 2.4 that an implementation must not decode the same string more than once. An application that normalizes or resolves an untrusted HTTP-family URI before outbound routing, redirect validation, or a host-policy check can receive a destination different from the one the original encoded host represented, giving a server-side request forgery and host-policy bypass primitive. This is an incomplete-fix variant of CVE-2026-6322. The affected versions are 2.4.1 up to but not including 2.4.5, 3.1.2 up to but not including 3.1.6, and 4.0.0 up to but not including 4.1.3. The issue is fixed in 2.4.5, 3.1.6, and 4.1.3, which normalize percent escapes once and preserve encoded percent signs. Users should upgrade to a patched version.
fast-uri >= 2.4.1, < 2.4.5fast-uri >= 3.1.2, < 3.1.6fast-uri >= 4.0.0, < 4.1.3Upgrade past the affected range:
fast-uri 4.1.3Affected packages:
fast-uri >= 2.4.1, < 2.4.5fast-uri >= 3.1.2, < 3.1.6fast-uri >= 4.0.0, < 4.1.3Patched in:
fast-uri 2.4.5fast-uri 3.1.6fast-uri 4.1.3Source: https://github.com/advisories/GHSA-fph4-wmhf-6fwf
Connected by shared product, vendor, weakness, or advisory.
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CVE-2026-6322High· 7.5fast-uri normalize() decoded percent-encoded authority delimiters inside the host component and then re-emitted them as raw delimiters during serialization
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