Ooh, so that's what Therac did? Or perhaps mangle the drive-by-wire software so that the stopping distance is just 10% longer - a few extra feet never killed anyone, eh? Or something non-life-threatening: silently truncate all passwords to 8 characters, not like anyone would abuse this to compromise the user (and it's the user's problem anyway, not the vendor's).
Irony aside: you are, perhaps unintentionally, omitting from your narative all and any damage that would be caused by such a deliberate bug - the vendor is usually the only one who can fix it, but not the only one who can exploit it. Also, what of unpatched devices, and of liability (you are introducing a backdoor, intentionally)? And realistically, your original change might introduce more holes than you bargained for, or the fix might. This is a horrible idea on so many levels, even discounting it's inherent evil.
Irony aside: you are, perhaps unintentionally, omitting from your narative all and any damage that would be caused by such a deliberate bug - the vendor is usually the only one who can fix it, but not the only one who can exploit it. Also, what of unpatched devices, and of liability (you are introducing a backdoor, intentionally)? And realistically, your original change might introduce more holes than you bargained for, or the fix might. This is a horrible idea on so many levels, even discounting it's inherent evil.