Kyverno hat SSRF über CEL http.Get/http.Post in NamespacedValidatingPolicy, das Zugriff auf Daten über Namespaces hinweg ermöglicht

The SSRF vulnerability in Kyverno allows an attacker with namespace-scoped policy creation permissions to craft malicious policies that make arbitrary HTTP requests. These requests originate from the Kyverno admission controller, effectively bypassing network segmentation and allowing access to resources that would normally be inaccessible. Specifically, an attacker could target internal services running within the Kubernetes cluster, potentially gaining unauthorized access to sensitive data or control. Furthermore, the vulnerability enables access to cloud metadata endpoints (e.g., 169.254.169.254 in AWS), which can expose credentials and configuration information. Data exfiltration is possible by embedding the results of these requests within policy error messages, effectively leaking data outside the cluster.

Organizations using Kyverno for policy enforcement in Kubernetes clusters are at risk, particularly those running versions 1.16.0 and above. Environments with extensive internal services and cloud integrations are especially vulnerable, as the SSRF vulnerability can be used to access sensitive data and credentials. Shared Kubernetes clusters with multiple namespaces and varying permission levels also increase the risk.

• linux / server:

journalctl -u kyverno -g 'http.Get' | grep -i '169.254.169.254'

• linux / server:

ps aux | grep kyverno | grep 'http.Get' 

• generic web:

curl -I <kyverno_admission_controller_endpoint> | grep 'Server: kyverno'

1. 2026-04-14Disclosure

   disclosure

1. Reserviert2026-03-24
2. Veröffentlicht2026-04-14
3. EPSS aktualisiert2026-04-07

The primary mitigation for CVE-2026-4789 is to upgrade Kyverno to version 1.17.0 or later, which contains the fix. If upgrading immediately is not feasible, consider implementing temporary workarounds. Restrict network access to the Kyverno admission controller to only necessary services. Implement network policies to limit the ability of Kyverno pods to make outbound requests. Monitor Kyverno logs for unusual HTTP requests originating from policy evaluations. While a WAF or proxy cannot directly prevent this SSRF, it can help detect and block suspicious outbound traffic patterns. No specific Sigma or YARA rules are readily available, but monitoring HTTP requests for unusual destinations is recommended.