Apache Struts REST Plugin uses an XStreamHandler with an instance of XStream for deserialization without any type filtering, which can lead to remote code execution when deserializing XML payloads.
When using a Spring AOP functionality to secure Struts actions it is possible to perform a DoS attack. Solution is to upgrade to Apache Struts version 2.5.12 or 2.3.33.
Apache Struts 2.3.19 to 2.3.20.2, 2.3.21 to 2.3.24.1, and 2.3.25 to 2.3.28, when Dynamic Method Invocation is enabled, allow remote attackers to execute arbitrary code via method: prefix, related to chained expressions.
The default exclude patterns (excludeParams) in Apache Struts 2.3.20 allow remote attackers to "compromise internal state of an application" via unspecified vectors.