CVE-2026-69192: ip-address: Address4 decodes leading-zero octets as decimal while resolvers decode them as octal, allowing SSRF and trust-boundary bypass

Address4 accepts an octet written with a leading zero and decodes it as decimal, while the WHATWG URL host parser, inet_aton, and getaddrinfo all decode a leading zero as octal. The library and the network stack therefore disagree about which host a string names. new Address4('012.0.0.1') reports correctForm() of 12.0.0.1 and isPrivate() of false, but fetch('http://012.0.0.1/') connects to 10.0.0.1.

An application that builds a network trust-boundary decision on these checks (for example a filter intended to block Server-Side Request Forgery, or SSRF) will classify an internal target as external and allow the request. SSRF is an attack in which a user-supplied address coaxes the server into making a request to an internal destination the user could not otherwise reach, such as a loopback service or a cloud metadata endpoint.