A critical remote code execution (RCE) vulnerability, identified as CVE-2025-1974, has been discovered in Kubernetes Ingress-NGINX controllers. This flaw, uncovered by security researchers at Wiz, affects the validation webhook component and could allow attackers to execute arbitrary code on affected systems, potentially compromising entire Kubernetes clusters.
Understanding the Vulnerability
Ingress-NGINX is a widely used ingress controller in Kubernetes environments, responsible for managing external access to services within a cluster. The vulnerability specifically targets the validation webhook server, which operates on port 8443 and is tasked with verifying and processing Ingress resources before their deployment.
The issue arises from insufficient validation within the `CheckIngress` function of the controller. By sending a specially crafted `AdmissionRequest` containing malicious NGINX configuration directives, an attacker can exploit this flaw to inject and execute arbitrary commands on the base system. This exploitation path is particularly concerning given the high privileges typically assigned to ingress controllers, including access to all secrets within the cluster.
Proof-of-Concept Demonstration
A proof-of-concept (PoC) exploit has been released, demonstrating how this vulnerability can be leveraged in a controlled minikube setup. The PoC illustrates the process of deploying a vulnerable pod and executing arbitrary commands through manipulated configuration files. This demonstration underscores the ease with which malicious actors could potentially exploit this flaw in real-world scenarios.
Potential Impact
The exploitation of CVE-2025-1974 could lead to unauthorized access to sensitive data, privilege escalation, and full control over affected Kubernetes clusters. Given that approximately 43% of cloud environments utilize Ingress-NGINX controllers, the scope of potential impact is substantial. Organizations with controllers exposed to the public internet are at immediate critical risk and should prioritize remediation efforts.
Mitigation Strategies
To protect against this vulnerability, organizations are advised to:
– Upgrade Immediately: Update Ingress-NGINX controllers to the latest patched version to address the vulnerability.
– Restrict Access: Implement network policies to limit access to the validation webhook server, reducing the attack surface.
– Monitor Logs: Regularly review controller logs for suspicious `AdmissionRequest` activities that could indicate exploitation attempts.
– Disable Webhook Temporarily: If immediate patching isn’t feasible, consider disabling the validation webhook as a temporary measure to mitigate risk.
The Kubernetes Security Special Interest Group (SIG) has confirmed the vulnerability and is collaborating with Ingress-NGINX maintainers to provide comprehensive patching and mitigation guidance.
Conclusion
The discovery of CVE-2025-1974 highlights the critical importance of vigilant monitoring and prompt patching in Kubernetes environments. Components that process external input, such as ingress controllers, are particularly susceptible to exploitation and should be secured accordingly. Organizations must take immediate action to mitigate this vulnerability and protect their Kubernetes clusters from potential compromise.
