The default configuration for cURL and libcurl before 7.42.1 sends custom HTTP headers to both the proxy and destination server, which might allow remote proxy servers to obtain sensitive information by reading the header contents.
http://curl.haxx.se/docs/adv_20150429.html
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10743
http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00017.html
http://www.debian.org/security/2015/dsa-3240
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
http://www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
http://www.oracle.com/technetwork/topics/security/cpuoct2015-2367953.html
http://www.securityfocus.com/bid/74408
http://www.securitytracker.com/id/1032233
http://www.ubuntu.com/usn/USN-2591-1
https://kc.mcafee.com/corporate/index?page=content&id=SB10131