CVE-2016-1906 in Kubernetes
Summary
by MITRE
The API server in Kubernetes might allow remote attackers to gain privileges by editing a build configuration to use a restricted strategy.
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Analysis
by VulDB Data Team • 07/07/2022
The vulnerability identified as CVE-2016-1906 affects the Kubernetes API server and represents a significant privilege escalation risk within container orchestration environments. This flaw exists in the build configuration handling mechanism of Kubernetes, specifically when the system processes requests to modify build strategies through the API interface. The vulnerability stems from inadequate access controls and validation checks within the API server's processing of build configuration objects, creating an opportunity for unauthorized actors to manipulate system behavior through crafted API requests.
The technical implementation of this vulnerability involves the API server's insufficient validation of build strategy modifications, particularly when users attempt to switch from standard build strategies to restricted ones. When a user with appropriate permissions submits a request to modify a build configuration, the system fails to properly verify whether the requested strategy transition is authorized or safe. This oversight allows attackers to potentially bypass security restrictions that would normally prevent certain build operations, effectively enabling them to execute privileged actions within the container orchestration environment.
From an operational impact perspective, this vulnerability can lead to severe consequences for organizations relying on Kubernetes for container management and deployment. An attacker who successfully exploits this vulnerability could potentially gain elevated privileges within the cluster, allowing them to execute arbitrary code, access sensitive data, or compromise other workloads running on the same infrastructure. The attack vector is particularly concerning because it leverages legitimate API functionality, making detection more difficult and potentially allowing attackers to remain undetected while escalating their privileges. The vulnerability affects the core security model of Kubernetes, undermining the trust boundaries that separate different user roles and system components.
Security professionals should implement multiple layers of defense to mitigate this vulnerability, including strict API access controls, comprehensive audit logging, and regular security assessments of container orchestration environments. The issue aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1078 for valid accounts and privilege escalation. Organizations should ensure that API server configurations enforce strict validation of all build strategy modifications, implement proper role-based access controls, and maintain continuous monitoring of API activity for suspicious behavior patterns. Additionally, regular updates and patches should be applied to maintain the latest security hardening measures, and security teams should conduct regular penetration testing to identify similar access control weaknesses in their Kubernetes deployments.