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CVE-2016-5386

30
FAUCET Score

CVE-2016-5386, known as "httpoxy," is a critical vulnerability in the net/http package of Go (through version 1.6) that affects products like Fedora, Golang, Oracle, and Red Hat. It allows remote attackers to redirect a CGI application's outbound HTTP traffic to an arbitrary proxy server by injecting a crafted Proxy header, exploiting a namespace conflict with the HTTP_PROXY environment variable. This vulnerability carries a high CVSS score of 8.1, indicating a high potential for impact (confidentiality, integrity, availability) with high attack complexity and no user interaction required. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion and media coverage, suggesting awareness despite its inactive status on the CISA KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
23CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:23:*:*:*:*:*:*:*
24CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:24:*:*:*:*:*:*:*
7CPE matchmatch criteria
cpe:2.3:o:oracle:linux:7:*:*:*:*:*:*:*
7.0CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
7.2CPE matchmatch criteria
cpe:2.3:o:redhat:enterprise_linux_server_aus:7.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.22%
Probability of exploitation in next 30 days
EPSS Percentile
91.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0522 is in the 61st percentile among its peer group of 8,915 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: golang-0:1.6.3-1.el7_2.1
View patch
redhatno patchvia redhat_api
Product: Red Hat OpenShift Enterprise 3Fixed in: golang
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux OpenStack Platform 7 (Kilo) Operational ToolsFixed in: golang
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 8 (Liberty) Operational ToolsFixed in: golang

Vendor Advisories (2)

redhatCVE-2016-5386Moderate

Go: sets environmental variable based on user supplied Proxy request header

Jul 18, 2016
microsoft2016-Jul/CVE-2016-5386Important

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.

Jul 12, 2016

References

rhn.redhat.com / errata/RHSA-2016-1538.html
Third Party Advisory
bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
h20566.www2.hpe.com / hpsc/doc/public/display
Third Party Advisory
httpoxy.org
Third Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/7WGHKKCFP4PLVSWQKCM3FJJPEWB5ZNTU
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/OR52UXGM6RKSCWF3KQMVZGVZVJ3WEESJ
kb.cert.org / vuls/id/797896
Third Party AdvisoryUS Government Resource
oracle.com / technetwork/security-advisory/cpujul2017-3236622.html
PatchThird Party Advisory
oracle.com / technetwork/topics/security/linuxbulletinjul2016-3090544.html
Third Party Advisory