Jenkins security and hardening out of the box

By default Jenkins Operator performs an initial security hardening of Jenkins instance via groovy scripts to prevent any security gaps.

Jenkins Access Control

Currently Jenkins Operator generates a username and random password and stores them in a Kubernetes Secret. However any other authorization mechanisms are possible and can be done via groovy scripts or configuration as code plugin. For more information take a look at the section on customizing Jenkins.

Any change to Security Realm or Authorization requires that user called jenkins-operator must have admin rights because Jenkins Operator calls Jenkins API.

Jenkins Hardening

The list below describes all the default security setting configured by the Jenkins Operator:

  • basic settings - use Mode.EXCLUSIVE - Jobs must specify that they want to run on master node
  • enable CSRF - Cross Site Request Forgery Protection is enabled
  • disable usage stats - Jenkins usage stats submitting is disabled
  • enable master access control - Slave to Master Access Control is enabled
  • disable old JNLP protocols - JNLP3-connect, JNLP2-connect and JNLP-connect are disabled
  • disable CLI - CLI access of /cli URL is disabled
  • configure kubernetes-plugin - secure configuration for Kubernetes plugin

If you would like to dig a little bit into the code, take a look here.

Jenkins API

The Jenkins Operator generates and configures Basic Authentication token for Jenkins Go client and stores it in a Kubernetes Secret.


Kubernetes API permissions are limited by the following roles:

Since Jenkins Operator must be able to grant permission for its deployed Jenkins masters to spawn pods (the Jenkins Master role above), the operator itself requires permission to create RBAC resources (the jenkins-operator role above).

Deployed this way, any subject which may create a Pod (including a Jenkins job) may assume the jenkins-operator role by using its’ ServiceAccount, create RBAC rules, and thus escape its granted permissions. Any namespace to which the jenkins-operator is deployed must be considered to implicitly grant all possible permissions to any subject which can create a Pod in that namespace.

To mitigate this issue, Jenkins Operator should be deployed in one namespace, and the Jenkins CR should be created in a separate namespace. For instructions on how to deploy Jenkins Operator and Jenkins in separate namespaces, head over to the Separate namespaces section of Getting Started guide.

Report a Security Vulnerability

If you find a vulnerability or any misconfiguration in Jenkins, please report it in the issues.

Last modified October 6, 2021