Executive brief
Calico, a networking and security solution for Kubernetes, contains a vulnerability where sensitive security tokens are accidentally written to system logs. An attacker with basic access to view container logs could steal these tokens to gain unauthorized control over other parts of the cluster. This could lead to unauthorized modifications of cluster workloads or further escalation of privileges within the environment.
Technical details
A vulnerability in the Calico 'install-cni' init container causes the rendered CNI configuration to be logged to stdout. In Canal or Flannel-Calico deployments using the __SERVICEACCOUNT_TOKEN__ placeholder, the installer substitutes the live Kubernetes ServiceAccount bearer token before logging. This exposes the token to any authenticated user with 'pods/log' permissions in the namespace containing the calico-node. The leaked token possesses 'patch' privileges on 'pods/status', which can be leveraged for annotation-based attacks against cluster workloads. This issue is a regression of a previous vulnerability (TTA-2018-001) and does not affect default kubeconfig-based authentication paths.
Affected products
- Tigera Calico >= 2.0.0, < 3.31.6
- Tigera Calico CNI Plugin < 1.11.0-cni-plugin.0.20260417001138-cd73bc2cea0f
Timeline
- 2026-05-28: disclosed
- 2026-05-28: advisory
- 2026-04-17: patched: Fix merged into master branch