CVE-2026-66787Network attack vector

Cross-cluster traffic interception via EndpointSlice spoofing

Published Aug 20, 2026 · Updated Aug 20, 2026

Improper input validation in Lighthouse in Red Hat ACM allows remote authenticated users to redirect cross-cluster traffic via EndpointSlices. Lighthouse trusts advertised addresses from imported EndpointSlice objects and returns them in DNS answers without verifying that the IPs belong to the exporting service or cluster. Exploitation requires control of a spoke cluster or comparable high privileges there, and it enables man-in-the-middle interception and modification of cross-cluster service data rather than code execution on peer clusters.

CVSS severity8.7
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Lighthouse in Red Hat ACM allows remote authenticated users to redirect cross-cluster traffic via EndpointSlices. Lighthouse trusts advertised addresses from imported EndpointSlice objects and returns them in DNS answers without verifying that the IPs belong to the exporting service or cluster. Exploitation requires control of a spoke cluster or comparable high privileges there, and it enables man-in-the-middle interception and modification of cross-cluster service data rather than code execution on peer clusters.

The record

CVE
CVE-2026-66787
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
389 Directory Server
Product
Red Hat Advanced Cluster Management for Kubernetes
Classifications
CWE-345, T1557
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

389 Directory Server · Red Hat Advanced Cluster Management for KubernetesAffected versions are unavailable in this record.

Published CVSS scores

8.7Red HatCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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