Npm · Ipaddress · CVE-2026-101910
**Name of the Vulnerable Software and Affected Versions**
ip-address versions 10.2.0 through 10.5.0
**Description**
The `Address6.isPrivate` classifier in `src/ipv6.ts` fails to recognize the NAT64 local-use range `64:ff9b:1::/48`. Consequently, the `isPrivate()`, `isLoopback()`, and `isLinkLocal()` functions return `false` for addresses within this range, causing internal IPv4 destinations encoded via a local-use NAT64 prefix to be incorrectly identified as global addresses. This can lead to a trust-boundary bypass in applications using these checks to prevent Server-Side Request Forgery (SSRF), an attack where a user-supplied address tricks a server into making requests to internal destinations, such as loopback services or cloud metadata endpoints. Exploitation requires the server network to use an operator-selected NAT64 prefix within the local-use range.
**Recommendations**
Update ip-address to version 10.5.1.
As a temporary workaround, manually test if a host is within the NAT64 local-use range by using `isHostInSubnet()` with the `64:ff9b:1::/48` subnet.