Zitadel is open-source identity infrastructure software. Prior to 4.6.0, 3.4.3, and 2.71.18, an attacker can perform an online brute-force attack on OTP, TOTP, and passwords. While Zitadel allows preventing online brute force attacks in scenarios like TOTP, Email OTP, or passwords using a lockout mechanism. The mechanism is not enabled by default and can cause a denial of service for the corresponding user if enabled. Additionally, the mitigation strategies were not fully implemented in the more recent resource-based APIs. This vulnerability is fixed in 4.6.0, 3.4.3, and 2.71.18.