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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.3 · 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 · score source

EPSS

• CVE-2026-101913: 0.39% estimated exploitation activity in the next 30 days; percentile 32.73 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Address6.isLinkLocal() recognizes fe80::/64 rather than fe80::/10. Link-local unicast is the whole /10 under RFC 4291 §2.4 and the IANA IPv6 Special-Purpose Address Registry, so the method returns false for every link-local address outside the one /64 that stateless address autoconfiguration happens to use. new Address6('fe81::1').isLinkLocal() is false. The library contradicts itself on the same object: for fe81::1, getType() returns 'Link-local unicast', getScope() returns 'Link local', and isHostInSubnet(new Address6('fe80::/10')) returns true, while isLinkLocal() returns false. An application that builds a network trust-boundary decision on these checks (for example a filter intended to block Server-Side Request Forgery, or SSRF) will classify a link-local target as unremarkable and allow the request. SSRF is an attack in which a user-supplied address coaxes the server into making a request to an internal destination the user could not otherwise reach. Details…

Published by the source

28 Sep 2026, 20:43 UTC

Last modified by the source

28 Sep 2026, 21:00 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-rpw4-54j3-4h4q

2. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-rpw4-54j3-4h4q

4. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-rpw4-54j3-4h4q

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# Patch Next advisory brief: CVE-2026-101913

Advisory: ip-address: Address6.isLinkLocal() recognizes fe80::/64 rather than fe80::/10, allowing SSRF and trust-boundary bypass to on-link hosts
IDs: CVE-2026-101913, GHSA-rpw4-54j3-4h4q
Record: https://patchnext.com/advisories/cve-2026-101913 (revision 4, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ip-address 10.5.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ip-address: affected <= 10.5.0; fixed in 10.5.1

## Suggested inspection (read-only)
- `npm ls ip-address --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ip-address.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rpw4-54j3-4h4q (GitHub-reviewed advisory GHSA-rpw4-54j3-4h4q lists affected ranges: npm ip-address >=0 <=10.5.0)
- Verified: https://osv.dev/vulnerability/GHSA-rpw4-54j3-4h4q (OSV record GHSA-rpw4-54j3-4h4q lists affected ranges: npm ip-address >=0 <10.5.1 (fixed))

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