Arch Linux Security Advisory ASA-201607-9
========================================
Severity: High
Date    : 2016-07-21
CVE-ID  : CVE-2016-5385
Package : drupal
Type    : proxy injection
Remote  : Yes
Link    : https://wiki.archlinux.org/title/CVE

Summary
======
The package drupal before version 8.1.7-1 is vulnerable to proxy
injection via environment variable.

Resolution
=========
Upgrade to 8.1.7-1.

# pacman -Syu "drupal>=8.1.7-1"

The problem has been fixed upstream in version 8.1.7.

Workaround
=========
Apache (.htaccess)

    
      RequestHeader unset Proxy
    

NGINX/FastCGI

    fastcgi_param HTTP_PROXY "";

For any other service please visit:
https://httpoxy.org/

Description
==========
Drupal 8 uses the third-party PHP library Guzzle for making server-side
HTTP requests. An attacker can provide a proxy server that Guzzle will
use. This vulnerability is called 'httpoxy'.  httpoxy is a set of
vulnerabilities that affect application code running in CGI, or CGI-like
environments. It comes down to a simple namespace conflict: 

RFC 3875 (CGI) puts the HTTP Proxy header from a request into the
environment variables as HTTP_PROXY HTTP_PROXY is a popular environment
variable used to configure an outgoing proxy This leads to a remotely
exploitable vulnerability. If you’re running PHP or CGI, you should
block the Proxy header now.

Impact
=====
A remote attacker is able to proxy the outgoing HTTP requests made by
the web application, direct the server to open outgoing connections to
an address and port of their choosing or tie up server resources by
forcing the vulnerable software to use a malicious proxy.

References
=========
https://access.redhat.com/security/cve/CVE-2016-5385
https://www.drupal.org/SA-CORE-2016-003
https://httpoxy.org/
https://bugzilla.redhat.com/show_bug.cgi?id=1353794