For CKEditor 4 related suggestions and bugs, you may report them in our CKEditor 4 issue tracker. Go to the Reporting Issues and Bugs and New Features articles for more information on how to make a report.
For any other product, contact us so we could report a feature request or a bug in our private repositories.
Note that the core development team defines the list of priorities so it is not possible to determine when a specific bug will be fixed. It is recommended that you keep a close eye on tickets that interest you.
For security issues that you find, send us a direct message that will include details and code samples. Our team will review it and, provided it turns out to be valid, they will work on a fix.