LibreChat: 2FA Re-enrollment Allows Full Account 2FA Takeover Without OTP Verification

LibreChat is an enhanced ChatGPT clone that supports multiple AI providers. Prior to 0.8.4-rc1, the GET /api/auth/2fa/enable endpoint can be called by an authenticated user (or attacker with a stolen session) even when 2FA is already fully enabled on the account. This endpoint overwrites the existing TOTP secret, generates new backup codes, and sets twoFactorEnabled to false — all without requiring any TOTP or backup code verification. An attacker with a valid session token can completely take over a victim's 2FA, locking the legitimate user out of their own two-factor authentication. This vulnerability is fixed in 0.8.4-rc1.