User Enumeration via Response Timing

ImpactThe 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.

PatchesThis vulnerability has been patched, implementing a timing-safe form login authenticator that ensures consistent response times regardless of whether a user exists or not.

Technical DetailsThe 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.

WorkaroundsNo workarounds are available. Users should upgrade to the patched version.

References * https://owasp.org/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/03-Identity_Management_Testing/04-Testing_for_Account_Enumeration_and_Guessable_User_Account