Libvirt Slaves Plugin provides a list of applicable credential IDs to allow users configuring the plugin to select the one to use. This functionality does not correctly check permissions, allowing any user with Overall/Read permission to get a list of valid credentials IDs. Those can be used as part of an attack to capture the credentials using another vulnerability.
Jenkins Libvirt Slaves Plugin does not perform permission checks on a method implementing form validation. This allows users with Overall/Read access to Jenkins to connect to an attacker-specified SSH server using attacker-specified credentials IDs obtained through another method, capturing credentials stored in Jenkins.
The form validation method does not require POST requests, resulting in a Cross-Site Request Forgery vulnerability (CSRF).