USR = 'johnson' // this may be scriptler parameter

hudson.model.Hudson.instance.items.each {jb ->
    sec = jb.getProperty(hudson.security.AuthorizationMatrixProperty.class)
    if (USR in sec?.groups) {     
    	prm = sec?.grantedPermissions.findAll{USR in it.value}.keySet().name
    	println "$jb.name: ${prm.sort().join ','}"
    }   
}
"FINISHED" // for don't print too large result in console

hudson_user_perms

Getting user's permissions in Hudson

Get user\'s permissions in hudson

Groovy