The Jakarta Multipart parser in Apache Struts 2 2.3.x before 2.3.32 and 2.5.x before 2.5.10.1 has incorrect exception handling and error-message generation during file-upload attempts, which allows remote attackers to execute arbitrary commands via a crafted Content-Type, Content-Disposition, or Content-Length HTTP header, as exploited in the wild in March 2017 with a Content-Type header containing a #cmd= string.
The URLValidator class in Apache Struts 2 2.3.20 through 2.3.28.1 and 2.5.x before 2.5.1 allows remote attackers to cause a denial of service via a null value for a URL field.
Apache Tiles 2.1 before 2.1.2, as used in Apache Struts and other products, evaluates Expression Language (EL) expressions twice in certain circumstances, which allows remote attackers to conduct cross-site scripting (XSS) attacks or obtain sensitive information via unspecified vectors, related to the (1) tiles:putAttribute and (2) tiles:insertTemplate JSP tags.