Security researchers have discovered a critical remote code execution vulnerability in the popular Apache Struts web application framework that could allow remote attackers to run malicious code on the affected servers.
By exploiting this vulnerability, it is possible to perform an RCE attack when namespace value isn't set for a result defined in underlying configurations and in the same time, its upper action(s) configurations have no or wildcard namespace. The same possibility when using url tag which doesn’t have value and action set and in the same time, its upper action(s) configurations have no or wildcard namespace.
Struts 2.3 - Struts 2.3.34
Struts 2.5 - Struts 2.5.16
The unsupported Struts versions may be also affected.
Recommended Course of Action
Upgrade to Struts 2.3.35 or Struts 2.5.17