PatchSiren cyber security CVE debrief
CVE-2026-41184 Tigera CVE debrief
A vulnerability in Calico's install-cni init container causes Kubernetes ServiceAccount bearer tokens to be logged to standard output when the CNI configuration template uses the __SERVICEACCOUNT_TOKEN__ placeholder. This affects Canal/Flannel-Calico deployments. The logged token grants patch privileges on pods/status, which can be exploited by any authenticated user with pods/log permission in the calico-node namespace to conduct annotation-based attacks against cluster workloads. The default kubeconfig-based authentication path is not affected. This vulnerability is a direct regression of TTA-2018-001.
- Vendor
- Tigera
- Product
- Calico
- CVSS
- MEDIUM 6
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-05-28
- Original CVE updated
- 2026-05-28
- Advisory published
- 2026-05-28
- Advisory updated
- 2026-05-28
Who should care
Kubernetes platform operators running Calico, Canal, or Flannel-Calico CNI plugins; security teams managing pod logging permissions; cluster administrators using __SERVICEACCOUNT_TOKEN__ authentication patterns
Technical summary
The install-cni init container in Calico logs its rendered CNI configuration to stdout for debugging purposes. When deployed in Canal or Flannel-Calico configurations that use the __SERVICEACCOUNT_TOKEN__ placeholder, the installer substitutes the live Kubernetes ServiceAccount bearer token into the configuration before logging occurs. This exposes the token to any principal with pods/log read access in the namespace containing calico-node. The exposed token carries patch privileges on pods/status, enabling attackers to modify workload annotations. The vulnerability does not affect deployments using the default kubeconfig-based authentication path. This represents a regression of previously addressed issue TTA-2018-001.
Defensive priority
medium
Recommended defensive actions
- Review Calico/Canal deployments for use of __SERVICEACCOUNT_TOKEN__ placeholder in CNI configuration templates
- Audit namespace-level pods/log permissions to identify overprivileged accounts
- Apply patches from referenced pull requests when available
- Monitor Tigera security bulletin TTA-2026-001 for official remediation guidance
- Consider log sanitization controls for init container output as defense in depth
Evidence notes
The vulnerability was disclosed via NVD on 2026-05-28 with status 'Undergoing Analysis'. Tigera's security bulletin TTA-2026-001 confirms this is a regression of TTA-2018-001. Three pull requests (12502, 12526, 12527) are referenced as remediation. The CVSS 4.0 vector indicates network attack vector with low attack complexity, requiring low privileges and no user interaction, with high confidentiality impact to the vulnerable component.
Official resources
2026-05-28