Improper Neutralization of Special Elements used in a Command ('Command Injection')
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.
Improper Input Validation
The `URLValidator` class in Apache Struts 2 allows remote attackers to cause a denial of service via a `null` value for a URL field.
Improper Input Validation
Apache Struts 2.x before 2.3.28 allows remote attackers to execute arbitrary code via a "%{}" sequence in a tag attribute, aka forced double OGNL evaluation.