http://struts.apache.org/2.0.11/docs/release-notes-2011.html
Communicate with users to make sure the following change doesn't impact them:
Struts 2.0.10 corrected a serious security flaw in the Struts 2 tags where using JSP EL expressions could allow malicious OGNL expressions through. All users are encouraged to upgrade to Struts 2.0.11. Note that existing pages that utilize JSP EL expressions with Struts 2 tags will no longer work as of this release.