When re-using a connection, curl was doing case insensitive comparisons of username 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.
{ "CWE": { "id": "CWE-178", "desc": "Improper Handling of Case Sensitivity" }, "package": "curl", "URL": "https://curl.se/docs/CVE-2016-8616.json", "severity": "Medium", "www": "https://curl.se/docs/CVE-2016-8616.html", "last_affected": "7.50.3" }