fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and…

Summary

fast-uri is a URI parser for Node.js. Its custom parser for bracketed IPv6 literals does not validate the complete IPv6 grammar, so invalid trailing text in an authority can be silently discarded and a malformed attacker-controlled host is turned into a different valid IPv6 destination. For example, a bracketed literal with invalid trailing characters is normalized to the unspecified address, which a Node HTTP client then connects to a local service over loopback, and other malformed literals c…