The Ad Injection WordPress plugin through 1.2.0.19 does not properly sanitize the body of the adverts injected into the pages, allowing a high privileged user (Admin+) to inject arbitrary HTML or javascript even with unfiltered_html disallowed, leading to a stored cross-site scripting (XSS) vulnerability. Further it is also possible to inject PHP code, leading to a Remote Code execution (RCE) vulnerability, even if the DISALLOW_FILE_EDIT and DISALLOW_FILE_MOD constants are both set.