Observable Response Discrepancy

Summary

Mautic is vulnerable to User Enumeration via Response Timing. The attacker can validate if a user exists by checking the time login returns. This timing difference can be used to enumerate valid usernames, after which an attacker could attempt brute force attacks. This vulnerability has been patched, implementing a timing-safe form login authenticator that ensures consistent response times regardless of whether a user exists or not. The vulnerability was caused by different response times when: * A valid username was provided (password hashing occurred). * An invalid username was provided (no password hashing occurred). The fix introduces a "TimingSafeFormLoginAuthenticator" that performs a dummy password hash verification even for non-existent users, ensuring consistent timing. No workarounds are available. Users should upgrade to the patched version. This issue affects mautic/core and mautic/core-lib versions through 5.2.7, 6.0.0-alpha through 6.0.4, and 7.0.0-alpha.