On April 24, 2014, the Struts developers announced that all versions of Struts prior to 126.96.36.199 are vulnerable to a serious security issue.
There is also a serious issue with the version of Apache FileUpload included with previous versions of Struts.
Upgrade to Struts 188.8.131.52 as soon as possible.
S2-021 Improves excluded params to avoid ClassLoader manipulation via ParametersInterceptor
S2-021 Adds excluded params to CookieInterceptor to avoid ClassLoader manipulation when the interceptors is configured to accept all cookie names (wildcard matching via "*")