The login form could be leveraged in a denial of service attack.
Impact
An attacker could use the login form to put the server under an excessive load. By doing so, Tuleap could be become innacessible to legitimate users.
CVSS2 score : 5 (AV:N/AC:L/Au:N/C:N/I:N/A:P)
Reference
https://www.owasp.org/index.php/Blocking_Brute_Force_Attacks