Rancher issues long-lived registration tokens to authenticate nodes and agents joining a downstream cluster. These tokens were stored and exposed in plaintext w…

CVE-2026-55997 affects Rancher, a Kubernetes management platform, which issues long-lived registration tokens for authenticating nodes and agents joining downstream clusters. These tokens are stored and exposed in plaintext with no expiration mechanism, creating a significant security risk. A malicious actor could obtain these tokens through multiple vectors including the Rancher API, etcd, stored automation scripts, or direct file access on a node. Once obtained, the token could be used at any time to register a rogue node into the cluster, potentially compromising the entire Kubernetes environment. The vulnerability enables unauthorized cluster access and node injection without time-limited token constraints. This issue is tracked by SUSE Bugzilla and has a corresponding GitHub security advisory. The lack of token expiration significantly increases the attack window and potential impact.