is it possible to use the latest spring security plugin in grails 2 app?
http://plugins.grails.org/plugin/grails/spring-security-core
If, by latest, you mean the current Grails 3 version of the Spring Security Plugin, then I'd say the quick answer is "no", it's not compatible with a Grails 2 application.
Plugins in Grails 2 and Grails 3 differ in form, installation scripts, etc. For instance, in Grails 2 you have to install the plugin, whereas in Grails 3 you just depend on the plugin.
That said, Grails 3 plugins are basically just zip/jar files, and you could try just depending on the Grails 3 plugin, which would get you the classes on your classpath at least, but none of the setup that Spring Boot performs when using that plugin in Grails 3. Furthermore, the plugin assumes Spring Boot and newer Spring libraries exist in your application (as they would in a Grails 3 app). You'd be buying a big chuck of dependency hell.
I'm not sure why you're trying to do this, but I don't recommend it.