CVE-2026-66785Network attack vector

Traffic hijacking via unvalidated endpoint subnets

Published Aug 20, 2026 · Updated Aug 25, 2026

Improper input validation in Submariner in Red Hat Advanced Cluster Management for Kubernetes lets remote authenticated users hijack peer traffic. The broker-to-local shouldSyncRemoteEndpoint hook accepts Endpoint.Spec.Subnets without binding them to the publishing cluster or checking them against declared and peer CIDRs, then installs them verbatim as WireGuard AllowedIPs or Libreswan rightSubnet values. Control of a connected spoke is required; a crafted broad CIDR redirects matching peer-cluster traffic into an attacker-controlled tunnel, enabling interception or disruption.

CVSS severity9.9
Critical
EPSS probability0.10%
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 Submariner in Red Hat Advanced Cluster Management for Kubernetes lets remote authenticated users hijack peer traffic. The broker-to-local shouldSyncRemoteEndpoint hook accepts Endpoint.Spec.Subnets without binding them to the publishing cluster or checking them against declared and peer CIDRs, then installs them verbatim as WireGuard AllowedIPs or Libreswan rightSubnet values. Control of a connected spoke is required; a crafted broad CIDR redirects matching peer-cluster traffic into an attacker-controlled tunnel, enabling interception or disruption.

The record

CVE
CVE-2026-66785
Published
Aug 20, 2026
Updated
Aug 25, 2026
Vendor
389 Directory Server
Product
Red Hat Advanced Cluster Management for Kubernetes
Classifications
CWE-20, T1557
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 privilegesauthenticated

What is affected?

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

Published CVSS scores

9.9Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
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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