EC-CUBE 3 series (3.0.0 to 3.0.18-p6) and 4 series (4.0.0 to 4.0.6-p3, 4.1.0 to 4.1.2-p2, and 4.2.0 to 4.2.2) contain an arbitrary code execution vulnerability due to improper settings of the template engine Twig included in the product. As a result, arbitrary code may be executed on the server where the product is running by a user with an administrative privilege.