Apache Commons BeanUtils, as distributed in lib/commons-beanutils-1.8.0.jar in Apache Struts 1.x through 1.3.10 and in other products requiring commons-beanutils through 1.9.2, does not suppress the class property, which allows remote attackers to "manipulate" the ClassLoader and execute arbitrary code via the class parameter, as demonstrated by the passing of this parameter to the getClass method of the ActionForm object in Struts 1.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.