isInSubnet() and isHostInSubnet() accept an address of either family and compare masked binary strings without checking that both operands are the same family. Address4 pads to 32 bits and Address6 to 128, so whenever the leading bits agree the strings are equal: new Address6('a00::1').isInSubnet(new Address4('10.0.0.0/8')) is true, and new Address4('32.0.0.1').isInSubnet(new Address6('2000::/3')) is true. No IPv4 address is inside an IPv6 network, so both answers are untrue. An application that parses …
new Address6() and Address6.isValid() place no bound on the length of the string they parse. When the string contains a character that cannot appear in an IPv6 address, the parser builds a diagnostic that wraps every such character in a 34-byte <span class="parse-error">, so the work and the memory scale with the input rather than with an address. A 1 MiB string of ! costs about 110 MB and 70 …
No classifier on Address6 recognizes the NAT64 local-use range 64:ff9b:1::/48 (RFC 8215). isPrivate(), isLoopback(), isLinkLocal() and their siblings all return false for every address in it, so an internal IPv4 destination written through a local-use NAT64 prefix (64:ff9b:1:7f00:0:100:: for 127.0.0.1, 64:ff9b:1:a9fe:a9:fe00:: for 169.254.169.254) reads as an ordinary global address. getType() names the range 'NAT64 (local-use)', so the library knows what the address is and classifies it as nothing. An application …
Address6.isLinkLocal() recognizes fe80::/64 rather than fe80::/10. Link-local unicast is the whole /10 under RFC 4291 §2.4 and the IANA IPv6 Special-Purpose Address Registry, so the method returns false for every link-local address outside the one /64 that stateless address autoconfiguration happens to use. new Address6('fe81::1').isLinkLocal() is false. The library contradicts itself on the same object: for fe81::1, getType() returns 'Link-local unicast', getScope() returns 'Link local', and isHostInSubnet(new Address6('fe80::/10')) returns true, …
Address6's special-property checks misclassify IPv4-mapped (::ffff:0:0/96) and NAT64 well-known (64:ff9b::/96) IPv6 addresses. These checks classify an address by its IPv6 wrapper rather than by the IPv4 address it embeds, so isLoopback(), isLinkLocal(), isMulticast(), and isUnspecified() all return false for literals such as ::ffff:127.0.0.1 or ::ffff:169.254.169.254 that actually route to loopback, RFC 1918, or link-local (cloud-metadata) destinations. Address6 also had no isPrivate() method, so a mapped RFC 1918 address could not …
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 …
Every special-use classification method is built on isInSubnet, which short-circuits to false whenever the address's own subnet mask is shorter than the reference range's mask. That mask comes verbatim from the CIDR suffix on the parsed input, so appending a suffix such as /0 suppresses classification entirely: isLoopback(), isPrivate(), isLinkLocal(), isCGNAT(), isMulticast(), isUnspecified(), isBroadcast(), isULA(), and getType() all report an internal address as unremarkable, while correctForm() and address still return …
Address6.group() and Address6.link() do not HTML-escape attacker-controlled content before embedding it in the HTML strings they return, and AddressError.parseMessage (emitted by the Address6 constructor for invalid input) can contain unescaped attacker-controlled content in one branch. An application that (1) passes untrusted input to Address6 and (2) renders the output of these methods, or the thrown error's parseMessage, as HTML (e.g. via innerHTML) is vulnerable to cross-site scripting. A related issue …