Description
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.
Remediation
References
http://struts.apache.org/docs/s2-029.html
http://www.securityfocus.com/bid/85066
http://www.securitytracker.com/id/1035271