Advisories for Gem/Devise-Two-Factor package

Devise-Two-Factor does not throttle or otherwise restrict login attempts at the server by default. When combined with the Time-based One Time Password algorithm's (TOTP) inherent entropy limitations, it's possible for an attacker to bypass the 2FA mechanism through brute-force attacks.

As a result of an incomplete fix for CVE-2015-7225, in versions of devise-two-factor prior to 4.0.2 it is possible to reuse a One-Time-Password (OTP) for one (and only one) immediately trailing interval. CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N)

In order to be fully RFC compliant for TOTPs, no valid OTP may be used more than once for a given timestep.