CVE-2026-115539

Name of the Vulnerable Software and Affected Versions SwarmKit versions prior to 2.1.3

Description The Cluster-API proxy can overwrite a forwarded client's TLS identity with the identity of an intermediary manager. This occurs because the WithMetadataForwardTLSInfo function replaces outgoing metadata with a copy of the incoming metadata, discarding changes made by the redirect guard when the application is built with grpc-go 1.39 or later. During a brief period following a leader change, if two proxy hops occur through managers with inconsistent views of the leader, an attacker with a valid worker node TLS certificate and private key can obtain a manager node certificate for their own key, resulting in a privilege escalation from worker to manager.

Recommendations Update SwarmKit to version 2.1.3.