Proxy Authentication Header Information Leakage
Project curl Security Advisory, August 3rd 2003 - Permalink
When curl connected to a site via an HTTP proxy with the CONNECT request, the user and password used for the proxy connection was also sent off to the remote server.
The Common Vulnerabilities and Exposures (CVE) project did not assign a name to this issue. securityfocus.com refers to it as BID 8432