Drupal 8.x < 8.1.7 PHP HTTP_PROXY Environment Variable Namespace Collision Vulnerability (httpoxy)
Medium Nessus Plugin ID 92495
Synopsis
A PHP application running on the remote web server is affected by a man-in-the-middle vulnerability.
Description
The version of Drupal running on the remote web server is 8.x prior to 8.1.7. It is, therefore, affected by a man-in-the-middle vulnerability known as 'httpoxy' due to a failure to properly resolve namespace conflicts in accordance with RFC 3875 section 4.1.18. The HTTP_PROXY environment variable is set based on untrusted user data in the 'Proxy' header of HTTP requests. The HTTP_PROXY environment variable is used by some web client libraries to specify a remote proxy server. An unauthenticated, remote attacker can exploit this, via a crafted 'Proxy' header in an HTTP request, to redirect an application's internal HTTP traffic to an arbitrary proxy server where it may be observed or manipulated.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Upgrade to Drupal version 8.1.7 or later.