A flaw was found in curl before version 7.51.0 When re-using a connection, curl was doing case insensitive comparisons of user name and password with the existing connections. This means that if an unused connection with proper credentials exists for a protocol that has connection-scoped credentials, an attacker can cause that connection to be reused if s/he knows the case-insensitive version of the correct password.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:LA:N3.7/CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NOther