CVE-2026-52865 in NGINX Ingress Controller
Summary
by MITRE • 07/15/2026
When NGINX Ingress Controller processes Ingress or TransportServer resources, an authenticated, remote attacker with permission to create or modify Ingress or TransportServer resources can cause the NGINX Ingress Controller process to terminate.
Impact: The NGINX Ingress Controller control plane process terminates and enters a persistent crash loop while the malformed Ingress or TransportServer resource remains in the cluster. This vulnerability allows a remote, authenticated attacker with at least Ingress or TransportServer resource write access to cause a denial-of-service (DoS) on the NGINX Ingress Controller system. There is no data plane exposure; this is a control plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical denial-of-service condition within the NGINX Ingress Controller control plane component, specifically affecting how the system processes Ingress and TransportServer resource configurations. The flaw arises from insufficient input validation mechanisms when handling resource modifications, allowing authenticated attackers with write permissions to craft malicious configurations that trigger process termination. The vulnerability exists entirely within the control plane domain, meaning it does not affect the data plane operations or direct network traffic handling capabilities of the ingress controller. This represents a significant operational risk as the affected process enters a persistent crash loop state, rendering the ingress controller unable to properly route traffic until manual intervention occurs.
The technical implementation of this vulnerability stems from inadequate error handling and resource validation within the NGINX Ingress Controller's configuration processing pipeline. When an attacker submits malformed or specially crafted Ingress or TransportServer resources, the controller fails to properly sanitize input data before attempting to process these configurations. This failure condition causes the underlying process to crash and restart repeatedly in a continuous loop, effectively disabling the ingress controller functionality. The vulnerability classifies under CWE-20 as a weakness related to improper input validation, specifically manifesting as an insufficient check for malformed input data during resource processing operations. The control plane nature of this flaw means that attackers do not need direct network access or elevated privileges beyond standard Kubernetes RBAC permissions required to create or modify ingress resources.
From an operational impact perspective, this vulnerability creates substantial disruption to service availability and system stability within Kubernetes environments utilizing NGINX Ingress Controller implementations. The persistent crash loop condition forces administrators to manually intervene by removing the problematic resource configurations, which can be time-consuming during high-traffic periods or emergency situations. The DoS condition affects the entire ingress controller deployment, potentially impacting multiple applications and services that depend on proper routing configuration. This vulnerability aligns with ATT&CK technique T1499.004 for endpoint denial of service, specifically targeting the availability aspect of control plane components rather than network infrastructure or application-level services. Organizations relying on NGINX Ingress Controller for traffic management face potential service disruption that could cascade into broader operational impacts across their Kubernetes deployments.
Mitigation strategies should focus on immediate implementation of enhanced input validation procedures and access control restrictions to limit exploitation opportunities. Organizations should enforce strict RBAC policies to minimize the number of users or applications with write permissions to ingress resources, implementing the principle of least privilege. The recommended approach involves upgrading to patched versions of NGINX Ingress Controller where appropriate, as well as implementing automated monitoring for crash loop conditions in ingress controller pods. Network segmentation and additional validation layers can provide defense-in-depth measures while awaiting official patches. Administrators should also establish incident response procedures that include rapid identification and removal of problematic ingress configurations, as well as maintaining detailed audit logs of ingress resource modifications to facilitate forensic analysis and prevent recurrence. The vulnerability highlights the importance of validating all external inputs within control plane components and implementing robust error handling mechanisms to prevent process termination under adverse conditions.