Rule Definition
Automatic filtering via a Struts bean has been turned off, which disables the Struts Validator and custom validation logic. This exposes the application to other weaknesses related to insufficient input validation.

Remediation
Set the validate field to true

Violation Code Sample

<action-mappings>
    <action path="/address"
            type="com.action.MainAction"
            name="myForm"            
            scope="request" 
            input="/addressInput.jsp" 
            validate="false">
        <forward name="success" path="/addressInput.jsp"/>
    </action>
</action-mappings>

Fixed Code Sample

<action-mappings>
    <action path="/address"
            type="com.action.MainAction"
            name="myForm"            
            scope="request" 
            input="/addressInput.jsp" 
            validate="true">
        <forward name="success" path="/addressInput.jsp"/>
    </action>
</action-mappings>

https://www.owasp.org/index.php/Improper_Data_Validation#Struts:_Validator_Turned_Off https://cwe.mitre.org/data/definitions/109.html