CVE-2026-13676High· 7.5▾ Twilightfast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor, silently leaving the host in its…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Jul 4.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.3%
Last analysed / modified upstream
0.3% → 0.5%
fast-uri versions 2.3.1 through 3.1.2 and 4.0.0 fail to canonicalize Unicode (IDN) hostnames for HTTP-family URLs. The IDN conversion path calls a helper that does not exist on the global URL constructor, silently leaving the host in its original Unicode form while normalize() and equal() still return values that differ from a WHATWG-compatible URL parser. Applications that use fast-uri to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) before passing the same URL to Node's URL or fetch can be bypassed when the two implementations resolve the same input to different hosts. Patches: upgrade to fast-uri 3.1.3 for the 3.x line or 4.0.1 for the 4.x line. Workarounds: enforce host policy using the same URL parser used for the actual request, or reject non-ASCII hosts before policy checks.
fast-uri >= 2.3.1, < 3.1.3fast-uri >= 4.0.0, < 4.0.1Upgrade past the affected range:
fast-uri 4.0.1Affected packages:
fast-uri >= 4.0.0, < 4.0.1fast-uri >= 3.0.0, < 3.1.3fast-uri >= 2.3.1, < 2.4.2Patched in:
fast-uri 4.0.1fast-uri 3.1.3fast-uri 2.4.2Connected by shared product, vendor, weakness, or advisory.
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
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-2026-86818Medium· 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-2026-33186Critical· 9.1gRPC-Go is the Go language implementation of gRPC
CVE-2026-86472Medium· 4.8fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv
CVE-2026-75931High· 7.5fast-uri: fast-uri: Host confusion via skipped IDN canonicalization (CVE-2026-75931)