CVE-2026-77180 - NGINX Ingress Controller Configuration Injection

CVE-2026-77180 represents a security vulnerability in the NGINX Ingress Controller for Kubernetes, arising from improper sanitization of Ingress annotations during the configuration generation process. An authenticated attacker who possesses the necessary privileges to create or update Kubernetes Ingress objects can supply malicious input within specific annotation fields. These inputs are subsequently incorporated into the generated NGINX configuration files without adequate validation, effectively allowing the attacker to inject arbitrary NGINX directives.

This issue is classified as a control plane vulnerability rather than a data plane exposure, meaning the impact is limited to the configuration logic of the ingress controller itself. Successful exploitation enables an attacker to manipulate server behavior, which may lead to service disruption, unauthorized modification of the NGINX configuration, or potential interaction with the underlying filesystem depending on the injected directives. Defenders should note that this vulnerability requires prior authorization within the Kubernetes cluster, making it an escalation or misuse path rather than a simple unauthenticated remote code execution.

Impact

The vulnerability allows for the modification of the NGINX Ingress Controller configuration, which can lead to service denial, arbitrary file system manipulation, or unauthorized changes to traffic routing rules within the cluster. Because it affects the control plane of the Kubernetes Ingress mechanism, the scope of impact is potentially cluster-wide for environments where users are granted broad permissions to manage Ingress resources.

Recommendation

• Implement strict Kubernetes RBAC policies to limit which users or service accounts have permission to create or update Ingress objects.
• Apply Admission Controllers or Validating Webhooks to sanitize or reject Ingress annotations containing suspicious characters (e.g., newline characters, semicolon delimiters, or unauthorized directive keywords).
• Update NGINX Ingress Controller to the latest security-patched release provided by the vendor.
• Review current Ingress configurations for unusual or non-standard annotation usage using the Kubernetes API audit logs.