Apache Struts 2.x before 2.3.28 allows remote attackers to execute arbitrary code via a "%{}" sequence in a tag attribute, aka forced double OGNL evaluation.
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.