The issue is related to a cross-site scripting (XSS) vulnerability in the implementation of the debug mode (devMode) in Apache Struts. This vulnerability can be exploited by a remote attacker to conduct inter-site script attacks. When the Struts2 debug mode is turned on, under certain conditions, an arbitrary script may be executed in the 'Problem Report' screen. Additionally, if JSP files are exposed to be accessed directly, it's possible to execute an arbitrary script.