---
id: CVE-2026-101910
title: >-
  ip-address is a library for parsing and manipulating IPv4 and IPv6 addresses
  in JavaScript
summary: >-
  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.
  Applicati…
severity: medium
cvss: 6.9
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:H/SI:N/SA:N'
cwe:
  - CWE-918
vendor: beaugunderson
product: ip-address
affected:
  - 'ip-address >= 10.2.0, < 10.5.1'
published: '2026-09-28'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T19:16:48.560'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-101910'
references:
  - url: >-
      https://github.com/beaugunderson/ip-address/commit/ab3dc88bcf5374344168a2ba075ca7ac4ff257f8
    label: security-advisories@github.com
  - url: 'https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/beaugunderson/ip-address/security/advisories/GHSA-2vr4-cq9g-pvrc
    label: security-advisories@github.com
  - url: >-
      https://github.com/beaugunderson/ip-address/security/advisories/GHSA-2vr4-cq9g-pvrc
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-28T18:12:11.522445Z'
cvssSource: cna
ingestedAt: '2026-09-28T18:17:54.308Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.