Oracle Linux: CVE-2016-5386: ELSA-2016-1538: golang security, bug fix, and enhancement update (MODERATE)

The net/http package in Go through 1.6 does not attempt to address RFC 3875 section 4.1.18 namespace conflicts and therefore does not protect CGI applications from the presence of untrusted client data in the HTTP_PROXY environment variable, which might allow remote attackers to redirect a CGI application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request, aka an "httpoxy" issue.
An input-validation flaw was discovered in the Go programming language built in CGI implementation, which set the environment variable "HTTP_PROXY" using the incoming "Proxy" HTTP-request header. The environment variable "HTTP_PROXY" is used by numerous web clients, including Go's net/http package, to specify a proxy server to use for HTTP and, in some cases, HTTPS requests. This meant that when a CGI-based web application ran, an attacker could specify a proxy server which the application then used for subsequent outgoing requests, allowing a man-in-the-middle attack.