bleepingcomputer[.]com/news/security/hidden-backdoor-in-tenda-router-firmware-grants-admin-access/
I've seen lots of Tenda brand routers listed on sites like Amazon & Newegg, so I figure there's people out there buying & using them. Turns out many of them have a backdoor coded into the firmware, which as far as anyone knows has not been fixed because they couldn't get ahold of anyone at the company.