HTTP_PROXY Environment Variable Namespace Collision Vulnerability (httpoxy)

high Nessus Plugin ID 92539


The remote web application is affected by a man-in-the-middle vulnerability.


The web application running on the remote web server is 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.


Applicable libraries and products should be updated to address this vulnerability. Please consult the library or product vendor for available updates.

If updating the libraries and products is not an option, or if updates are unavailable, filter 'Proxy' request headers on all inbound requests.

See Also

Plugin Details

Severity: High

ID: 92539

File Name: http_httpoxy.nasl

Version: 1.14

Type: remote

Family: Web Servers

Published: 7/25/2016

Updated: 4/11/2022

Risk Information

CVSS Score Source: CVE-2016-5386


Risk Factor: Medium

Score: 6.7


Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.3

Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P

Temporal Vector: E:POC/RL:OF/RC:C


Risk Factor: High

Base Score: 8.1

Temporal Score: 7.3

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:php:php, cpe:/a:golang:go, cpe:/a:apache:http_server, cpe:/a:apache:tomcat, cpe:/a:drupal:drupal, cpe:/a:python:python, cpe:/a:facebook:hiphop_virtual_machine

Exploit Available: true

Exploit Ease: Exploits are available

Exploited by Nessus: true

Patch Publication Date: 7/18/2016

Vulnerability Publication Date: 7/18/2016

Reference Information

CVE: CVE-2016-5385, CVE-2016-5386, CVE-2016-5387, CVE-2016-5388, CVE-2016-1000109, CVE-2016-1000110

BID: 91815, 91816, 91818, 91821

CERT: 797896