CVE-2026-71577 in Multicluster Global Hub
Summary
by MITRE • 08/10/2026
A flaw was found in multicluster-global-hub. During a ManagedClusterMigration, the system incorrectly grants all managed hubs read access to a shared communication topic. This allows a compromised managed hub to intercept and collect sensitive bootstrap kubeconfigs, which contain API server tokens intended for other hubs. These tokens have an extended validity of approximately 9.86 years, significantly increasing the risk of unauthorized access and information disclosure to other managed clusters.
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Analysis
by VulDB Data Team • 08/10/2026
This vulnerability resides within the multicluster-global-hub architecture where a critical misconfiguration occurs during ManagedClusterMigration operations. The flaw represents a severe privilege escalation issue that fundamentally undermines the security boundaries between managed clusters and their respective communication channels. When a migration process executes, the system fails to properly isolate the communication topics that are shared across multiple hubs, creating an unintended access pathway that violates core security principles of cluster separation and data protection.
The technical implementation error manifests as improper access control enforcement during cluster transition phases. Specifically, the system grants excessive read permissions on shared communication topics without considering the security context of individual managed hubs. This misconfiguration creates a persistent backdoor where any compromised managed hub can traverse the network boundary to access sensitive bootstrap kubeconfigs that should remain isolated to their originating clusters. The vulnerability exploits fundamental concepts of secure multi-tenancy and cluster segmentation, allowing lateral movement through the communication infrastructure.
The operational impact of this flaw extends far beyond simple information disclosure, creating a persistent threat vector that could remain active for extended periods due to the extraordinarily long token validity period of approximately 9.86 years. This prolonged exposure window significantly increases the attack surface and provides adversaries with substantial time to establish persistent access and conduct reconnaissance operations across multiple clusters. The bootstrap kubeconfigs contain critical API server tokens that can be leveraged to gain administrative control over target clusters, potentially enabling complete compromise of the multi-cluster environment.
This vulnerability aligns with CWE-284 (Improper Access Control) and represents a classic case of privilege escalation through improper resource sharing. From an attack perspective, it maps directly to several ATT&CK techniques including T1078 (Valid Accounts), T1566 (Phishing), and T1046 (Network Service Scanning) where attackers could exploit this weakness to establish footholds in multiple clusters simultaneously. The long token validity period exacerbates the risk profile by creating a window where even if initial compromise is detected and remediated, the compromised tokens can continue to provide access.
The mitigation strategy requires immediate implementation of granular access controls that enforce proper isolation during migration operations and throughout normal cluster lifecycle management. Organizations should implement strict topic-level permissions that prevent cross-cluster reading of bootstrap configurations and establish automated monitoring for unauthorized access patterns. Additionally, token rotation mechanisms should be implemented to reduce the effective lifetime of these critical credentials, while network segmentation policies should be strengthened to ensure that communication topics remain properly isolated between managed clusters. Regular security audits of migration procedures and access control configurations are essential to prevent recurrence of similar issues in other system components.