The MailUp Auto Subscription plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.1.0. This is due to missing or incorrect nonce validation on the masoptions function. This makes it possible for unauthenticated attackers to update settings and inject malicious web scripts via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

ajax.functions.php in the MailUp plugin before 1.3.3 for WordPress does not properly restrict access to unspecified Ajax functions, which allows remote attackers to modify plugin settings and conduct cross-site scripting (XSS) attacks by setting the wordpressloggedin cookie. NOTE: this is due to an incomplete fix for a similar issue that was fixed in 1.3.2.

ajax.functions.php in the MailUp plugin before 1.3.2 for WordPress does not properly restrict access to unspecified Ajax functions, which allows remote attackers to modify plugin settings and conduct cross-site scripting (XSS) attacks via unspecified vectors related to "formData=save" requests, a different version than CVE-2013-0731.