Jenkins Mattermost Notification Plugin 2.7.0 and earlier stored webhook URLs containing a secret token unencrypted in its global configuration file and job config.xml files on the Jenkins master where they could be viewed by users with Extended Read permission, or access to the master file system.

A server-side request forgery vulnerability exists in Jenkins Mattermost Notification Plugin 2.6.2 and earlier in MattermostNotifier.java that allows attackers with Overall/Read permission to have Jenkins connect to an attacker-specified Mattermost server and room and send a message.