Jenkins OctopusDeploy Plugin stores credentials unencrypted in its global configuration file on the Jenkins master where they can be viewed by users with access to the master file system.
A server-side request forgery vulnerability exists in Jenkins OctopusDeploy Plugin 1.8.1 and earlier in OctopusDeployPlugin.java that allows attackers with Overall/Read permission to have Jenkins connect to an attacker-specified URL and obtain the HTTP response code if successful, and exception error message otherwise.