Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to an issue in the Jenkins user database authentication realm: create an account if signup is enabled; or create an account if the victim is an administrator, possibly deleting the existing default admin user in the process and allowing a wide variety of impacts.

Jenkins versions 2.56 and earlier as well as 2.46.1 LTS and earlier are vulnerable to a login command which allowed impersonating any Jenkins user. The login command available in the remoting-based CLI stored the encrypted user name of the successfully authenticated user in a cache file used to authenticate further commands. Users with sufficient permission to create secrets in Jenkins, and download their encrypted values (e.g. with Job/Configure permission), were able to impersonate any other Jenkins user on the same instance.