fast-uri vulnerable to host confusion via failed IDN canonicalization

Impact fast-uri versions = 2.3.1, = 4.0.0 fail to canonicalize Unicode/IDN hostnames for HTTP-family URLs. The IDN conversion path calls URL.domainToASCII... on the global WHATWG URL constructor, where that helper does not exist. The resulting TypeError is silently routed into parsed.error, but...

CVE-2026-13676

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...