CVE-2026-101910

ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. From 10.2.0 until 10.5.1, the Address6 isPrivate classifier in src/ipv6.ts does not recognize the NAT64 local-use range 64:ff9b:1::/48. Applications that combine isPrivate, isLoopback, and isLinkLocal for a trust-boundary decision can treat an internal IPv4 destination encoded through that range as external. Exploitation depends on a server network using an operator-selected NAT64 prefix within the local-use range. A successful bypass can cross the intended network trust boundary. This issue is fixed in version 10.5.1.

• https://github.com/beaugunderson/ip-address/commit/ab3dc88bcf5374344168a2ba075ca7ac4ff257f8
• https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1
• https://github.com/beaugunderson/ip-address/security/advisories/GHSA-2vr4-cq9g-pvrc
• https://github.com/beaugunderson/ip-address/security/advisories/GHSA-2vr4-cq9g-pvrc