In Apache Wicket 1.5.10 or 6.13.0, by issuing requests to special urls handled by Wicket, it is possible to check for the existence of particular classes in the classpath and thus check whether a third party library with a known security vulnerability is in use.

Apache Wicket before 1.5.12, 6.x before 6.17.0, and 7.x before 7.0.0-M3 might allow remote attackers to obtain sensitive information via vectors involving identifiers for storing page markup for temporary user sessions.