ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. Prior to 10.5.1, the Address6 isLinkLocal method in src/ipv6.ts recognizes only fe80::/64 instead of the complete fe80::/10 IPv6 link-local range. An attacker-controlled address elsewhere in fe80::/10 can therefore pass a trust-boundary check that relies on isLinkLocal. The same address is identified as link-local by getType and getScope, exposing the inconsistent classification. A successful bypass can reach an on-link host outside the intended trust boundary. This issue is fixed in version 10.5.1.
https://github.com/beaugunderson/ip-address/security/advisories/GHSA-rpw4-54j3-4h4q
https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1
https://github.com/beaugunderson/ip-address/commit/d03e960c7cc3179ef25c8a44b4f94dd499625546
Published: 2026-09-28
Updated: 2026-09-28
Base Score: 6.4
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:N
Severity: Medium
Base Score: 9.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Severity: Critical
Base Score: 6.3
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
Severity: Medium
EPSS: 0.00386