CVE-2026-55723
HighCVSS 8.3Exploitation Probability (EPSS)
Low risk21th percentile - higher than 21% of all known CVEs
Summary
An injection vulnerability exists in NGINX Ingress Controller when configured with CRDs or Ingress annotations. An authenticated attacker with write access can inject arbitrary NGINX configuration directives.
Risk Assessment
The risk includes injection of arbitrary NGINX directives, file creation or deletion, and service disruption, potentially compromising the control plane integrity and availability.
Recommendation
Immediately update NGINX Ingress Controller to the latest version and restrict write access to CRDs and Ingress annotations to trusted users only.
Other vulnerabilities in NGINX Ingress Controller
See all- CVE-2026-104939High
NGINX Ingress Controller has a vulnerability when implementing an externalAuth policy for ingress. NGINX Ingress Controller may mishandle the HTTP response from an OAuth IdP and allow an attacker to acquire unauthenticated access to protected paths before the proper external authentication can happen.
- CVE-2026-77180High
A vulnerability in NGINX Ingress Controller where the configuration generator does not sanitize user-controllable fields from Ingress annotations. An authenticated attacker with permission to create or modify these annotations can inject arbitrary NGINX configuration directives.
- CVE-2026-52865Medium
A vulnerability in NGINX Ingress Controller allows an authenticated attacker with permissions to create or modify Ingress or TransportServer resources to terminate the controller process. This causes a persistent crash loop until the malformed resource is removed from the cluster.
Original NVD description (English source)
When NGINX Ingress Controller is configured with Custom Resource Definitions (CRDs) or Ingress annotations, an injection vulnerability exists in the configuration generator of NGINX Ingress Controller. Multiple user-controllable fields are written into the generated NGINX configuration without sanitization. An authenticated attacker with permission to create or modify these CRDs or annotations may craft values that inject arbitrary NGINX configuration directives. Impact: An authenticated attacker granted write access to NGINX Ingress Controller CRDs or Ingress annotations through the Kubernetes API may be able to inject arbitrary NGINX configuration directives, create or delete files, or disable services. 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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS