CVE-2026-101912: ip-address: isInSubnet() and isHostInSubnet() compare addresses of different families as if they shared an address space, allowing an allowlist check to admit an address outside its range

Medium severity · published Sep 28, 2026

CVE-2026-101912

ip-address: isInSubnet() and isHostInSubnet() compare addresses of different families as if they shared an address space, allowing an allowlist check to admit an address outside its range

6.3

CVSS

0.4%

EPSS

On KEV

Description

ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses in JavaScript. Prior to 10.7.1, the isInSubnet and isHostInSubnet methods in src/common.ts compare masked binary strings without validating that both operands use the same IP family. A cross-family containment check whose leading address bits match makes the masked strings compare equal even though IPv4 and IPv6 do not share an address space. An allowlist or denylist decision can therefore classify an address outside the intended range as contained. This issue is fixed in version 10.7.1.

Exploitation

Is it being used?

Exploit prediction (EPSS)0.4% · higher than 31% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

ip-address · beaugunderson

< 10.7.1 · source: vendor

Affected product

ip-address