Review the report (listed below) and make corrections to prevent it from being exploitable
Perform a full security and standards review on your own code
Install Plugin Check and run it against your plugin. IMPORTANT NOTE: All issues it finds must be fixed before your plugin will be re-reviewed or able to be re-listed in the Plugin Directory, regardless of their connection to the initial reported security vulnerability.
Increase the plugin version
Ensure the 'tested up to' version in your readme is the latest release of WordPress
Update the code in SVN (do not send us a link to a repo or dropbox or a zip of the new files)