Probably on the verge of paranoia, but might be a reason to rate limit 2FA validation attempts
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Or why you should not rely on automated phone calls as a method to reach the user and reset passwords, 2FA or for any kind of verification. Not unlike SMS-based 2FA, it is currently insecure and can be compromised by the way of its weakest link: voicemail systems
The primary source of account hacks is password spraying (on legacy auth like SMTP, IMAP, POP, etc.), second is replay attack. Takeaway: password are insecure, use and enforce MFA