A very popular WordPress plugin was hacked over the weekend after a hacker defaced its website and sent a mass message to all its customers revealing the existence of supposed unpatched security holes. In a follow-up mass email, the plugin's developers blamed the hack on a former employee, who also defaced their website. The plugin in question is WPML (or WP MultiLingual), the most popular WordPress plugin for translating and serving WordPress sites in multiple languages. According to its website, WPML has over 600,000 paying customers and is one of the very few WordPress plugins that is so reputable that it doesn't need to advertise itself with a free version on the official WordPress.org plugins repository. But on Saturday, ET timezone, the plugin faced its first major security incident since its launch in 2007. The attacker, which the WPML team claims is a former employee, sent out a mass email to all the plugin's customers. In the email, the attacker claimed he was a security researcher who reported several vulnerabilities to the WPML team, which were ignored. The email[1, 2, 3, 4, 5] urged customers to check their sites for possible compromises.