CVE-2026-84292High· 7.5▾ Twilightfast-uri serializes the port component of a URI without validating it. When recomposing the authority, the userinfo and host components are escaped but the port is concatenated verbatim, so a port value that is not a sequence of digits c…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0 · exploitation 0
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Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
fast-uri serializes the port component of a URI without validating it. When recomposing the authority, the userinfo and host components are escaped but the port is concatenated verbatim, so a port value that is not a sequence of digits can inject authority delimiters, demoting the intended host to userinfo and pointing the authority at an attacker-controlled host. Both fast-uri and Node's URL read the result back as the attacker's host with no error, so re-validating the built URI does not catch it. This affects applications that build URIs from parts and assign untrusted data to the port component through the serialize, normalize, or equal functions in their object forms. The issue affects fast-uri versions before 2.4.6, from 3.0.0 before 3.1.7, and from 4.0.0 before 4.1.4. It is fixed in 2.4.6, 3.1.7, and 4.1.4, where recomposeAuthority rejects any port that is not a digit sequence per RFC 3986.
fast-uri < 2.4.6fast-uri >= 3.0.0, < 3.1.7fast-uri >= 4.0.0, < 4.1.4Upgrade past the affected range:
fast-uri 4.1.4Affected packages:
fast-uri < 2.4.6fast-uri >= 3.0.0, < 3.1.7fast-uri >= 4.0.0, < 4.1.4Patched in:
fast-uri 2.4.6fast-uri 3.1.7fast-uri 4.1.4Connected by shared product, vendor, weakness, or advisory.
CVE-2026-84394High· 7.5fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority
CVE-2026-13676High· 7.5fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-family URLs
CVE-2026-86818Medium· 4.8fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv, that added a mailto scheme parser in version 4.1.3
CVE-2026-86472Medium· 4.8fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv
CVE-2026-6321High· 7.5fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions
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