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.
https://www.tenable.com/security/tns-2016-21
https://security.gentoo.org/glsa/201701-47
https://curl.haxx.se/docs/adv_20161102B.html
https://curl.haxx.se/CVE-2016-8616.patch
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2016-8616
https://access.redhat.com/errata/RHSA-2018:3558
https://access.redhat.com/errata/RHSA-2018:2486
http://www.securitytracker.com/id/1037192
http://www.securityfocus.com/bid/94094
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html