Phase: Architecture and Design
Avoid adding user-controlled data into an expression interpreter when possible.
Phase: Implementation
- Validate that the user input will not evaluate as an expression
- Encode the user input in a way that ensures it is not evaluated as an expression
Phase: System Configuration; Operation
The framework or tooling might allow the developer to disable or deactivate the processing of EL expressions, such as setting the isELIgnored attribute for a JSP page to "true".