MISP: HTTP Method Bypass of Login Security Controls (Bruteforce Protection and Email OTP)

The login() function in MISP's UsersController.php contained insufficient HTTP method validation for several security-critical code paths. The original code used an allowlist approach, checking only for specific HTTP methods (POST and PUT) before enforcing bruteforce protection, email one-time-password (OTP) verification, and login-failure logging. Because the checks were not exhaustive, an unauthenticated attacker could issue login requests using other HTTP methods and bypass all three security controls simultaneously. Specifically:   - the bruteforce blocklisting check and attempt counter were skipped, allowing unlimited credential-guessing attempts without being rate-limited or blocked  -  the email OTP two-factor authentication step was skipped, defeating the second factor of authentication  - login-failure events were neither logged nor counted, removing the audit trail and the mechanism that would normally trigger a blocklist entry. The security impact is the effective disabling of brute-force protection and multi-factor authentication for any attacker who can craft an HTTP request with a non-POST/PUT method to the login endpoint, potentially leading to credential compromise and unauthorized access to the MISP instance. Version affected: <2.5.47

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.