A host header attack vulnerability exists in FUEL CMS 1.5.0 through fuel/modules/fuel/config/fuel_constants.php and fuel/modules/fuel/libraries/Asset.php. An attacker can use a man in the middle attack such as phishing.
FUEL CMS 1.4.8 allows SQL injection via the 'fuel_replace_id' parameter in pages/replace/1. Exploiting this issue could allow an attacker to compromise the application, access or modify data, or exploit latent vulnerabilities in the underlying database.
In FUEL CMS 11.4.12 and before, the page preview feature allows an anonymous user to take complete ownership of any account including an administrator one.