Denial-of-service (DoS) vulnerability in the Multi-Factor Authentication module in Liferay DXP 7.3 before fix pack 1 allows remote authenticated attackers to prevent any user from authenticating by (1) enabling Time-based One-time password (TOTP) on behalf of the other user or (2) modifying the other user's TOTP shared secret.

The SimpleCaptcha implementation in Liferay Portal 7.3.4, 7.3.5 and Liferay DXP 7.3 before fix pack 1 does not invalidate CAPTCHA answers after it is used, which allows remote attackers to repeatedly perform actions protected by a CAPTCHA challenge by reusing the same CAPTCHA answer.