CVE-2026-66785: Submariner: submariner: missing validation of remote endpoint subnets and clusterid enables cross-cluster traffic hijack

Severity: high (CVSS 8.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-20 · updated 2026-10-19
Weakness: CWE-345

Description

A flaw was found in Submariner. This vulnerability allows a malicious cluster (spoke) to redirect network traffic from other connected clusters (peer clusters) by publishing a specially crafted network endpoint. The system fails to properly validate the network subnets provided by the malicious cluster, enabling it to declare arbitrary network ranges. Consequently, all network traffic intended for these arbitrary ranges from peer clusters will be rerouted through the attacker's tunnel, potentially leading to unauthorized information disclosure or network disruption.

Affected products

Red Hat Advanced Cluster Management for Kubernetes 2: all versions
Red Hat Advanced Cluster Management for Kubernetes 2.16: all versions — fixed in 1790670231, 1790670233, 1790670243, 1790670254, 1790670439, 1790670508
Red Hat Advanced Cluster Management for Kubernetes 2.17: all versions — fixed in 1788023916, 1788023940, 1788043961, 1788043964, 1788043970, 1788073481

How to fix

Upgrade to a fixed version: Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670231, 1790670233, 1790670243, 1790670254; Red Hat Advanced Cluster Management for Kubernetes 2.17 1788023916, 1788023940, 1788043961, 1788043964. Check the vendor advisory for mitigations.

References

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