# CVE-2026-101913: ip-address Address6 isLinkLocal incomplete subnet check

Source: https://junglewise.ai/threats/cve-2026-101913-ip-address-is-a-library-for-parsing-and-manipulating-ipv4-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-28. Updated: 2026-09-28  
License: CC BY 4.0 with a link back

CVE-2026-101913 · Severity: medium · CVSS 4 · Published 2026-09-28

The ip-address JavaScript library was incorrectly recognizing IPv6 link-local addresses. Applications that use the isLinkLocal method for security decisions—such as deciding whether to trust traffic from a particular address—would incorrectly accept addresses outside the intended range. An attacker could exploit this to bypass address-based access controls and reach systems that should only accept on-link traffic.

Technologies: [ip-address (npm)](https://junglewise.ai/threats/technologies/ip-address). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-101913 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101913 being exploited in the wild.

**How severe is CVE-2026-101913?** Medium severity, with a CVSS score of 4, published 28 September 2026.

**Which products and versions are affected?** ip-address (npm) <= 10.5.0, SEMVER:introduced=0,fixed=10.5.1; Ip-Address before 10.5.1.

**Is there a fix for CVE-2026-101913?** Yes. ip-address (npm): upgrade to 10.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-101913 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101913?** Check whether you run ip-address (npm) or Ip-Address at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- ip-address (npm): upgrade to 10.5.1 or later

  ```sh
  npm install ip-address@10.5.1
  ```


## Technical details

The Address6 isLinkLocal method in src/ipv6.ts checked only the fe80::/64 subnet instead of the complete fe80::/10 range defined by RFC 4291. This caused addresses in fe80::/10 but outside fe80::/64 to fail the isLinkLocal check despite being classified as link-local by getType and getScope, creating an inconsistency that allowed trust-boundary bypasses when address type was used for network access control.

## Affected products

- ip-address before 10.5.1

## Identifiers

- CVE-2026-101913
- GHSA-rpw4-54j3-4h4q

## Timeline

- 2026-09-28: disclosed
- 2026-08-29: patched: Version 10.5.1 released

## References

- [https://github.com/beaugunderson/ip-address/commit/d03e960c7cc3179ef25c8a44b4f94dd499625546](https://github.com/beaugunderson/ip-address/commit/d03e960c7cc3179ef25c8a44b4f94dd499625546)
- [https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1](https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1)

## Related threats

- [ip-address Address6 regex denial of service](https://junglewise.ai/threats/duplicate-advisory-ip-address-address6-matches-a-zone-identifier-in-9feed89f)
- [ip-address Address6 quadratic regex denial of service](https://junglewise.ai/threats/cve-2026-111997-ip-address-before-10-7-4-allows-a-denial-of-service-cpu)
- [ip-address logic error in subnet containment check](https://junglewise.ai/threats/cve-2026-101912-ip-address-is-a-library-for-parsing-and-manipulating-ipv4-and)
- [ip-address denial of service in Address6 constructor](https://junglewise.ai/threats/cve-2026-101911-ip-address-is-a-library-for-parsing-and-manipulating-ipv4-and)
- [ip-address library Address6 trust boundary bypass via NAT64 range](https://junglewise.ai/threats/cve-2026-101910-ip-address-is-a-library-for-parsing-and-manipulating-ipv4-and)