Hiding a backdoor requires hiding it from every user who might publicize it, not some users. Your issue (which is barely a vulnerability at all, in my personal

Hiding a backdoor requires hiding it from every user who might publicize it, not some users. Your issue (which is barely a vulnerability at all, in my personal opinion) demonstrates a failure to hide a vulnerability, if you think it was intentionally-placed (which I don't), in that you quickly learned about it.