The Windows installer for Apache Tomcat 6.0.0 through 6.0.20, 5.5.0 through 5.5.28, and possibly earlier versions uses a blank default password for the administrative user, which allows remote attackers to gain privileges.
Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, 6.0.0 through 6.0.18, and possibly earlier versions normalizes the target pathname before filtering the query string when using the RequestDispatcher method, which allows remote attackers to bypass intended access restrictions and conduct directory traversal attacks via .. (dot dot) sequences and the WEB-INF directory in a Request.
Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18 permits web applications to replace an XML parser used for other web applications, which allows local users to read or modify the (1) web.xml, (2) context.xml, or (3) tld files of arbitrary web applications via a crafted application that is loaded earlier than the target application.