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CVE-2016-5284

24
FAUCET Score

CVE-2016-5284 describes a vulnerability in Mozilla Firefox, Firefox ESR, and Thunderbird versions prior to 49.0 and 45.4 respectively, where incorrect expiration dates for Preloaded Public Key Pinning could allow man-in-the-middle (MitM) attacks. An attacker could exploit this by spoofing add-on updates using an X.509 certificate for addons.mozilla.org signed by any trusted Certification Authority. This vulnerability has a CVSS v3 score of 7.4 (HIGH), indicating a network-based attack with low complexity, requiring user interaction, and potentially leading to high confidentiality impact. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 48.0.2CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
45.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.0:*:*:*:*:*:*:*
45.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.0.1:*:*:*:*:*:*:*
45.0.2CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.0.2:*:*:*:*:*:*:*
45.1.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:45.1.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.4HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
4.0
CvssVersion
3.0

Exploit Intelligence

EPSS Score
2.37%
Probability of exploitation in next 30 days
EPSS Percentile
82.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0237 is in the 81st percentile among its peer group of 14,855 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: firefox-0:45.4.0-1.el5_11
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: firefox-0:45.4.0-1.el6_8
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox-0:45.4.0-1.el7_2
View patch

Vendor Advisories (1)

redhatCVE-2016-5284Important

Mozilla: Add-on update site certificate pin expiration (MFSA 2016-85, MFSA 2016-86)

Sep 20, 2016

References

rhn.redhat.com / errata/RHSA-2016-1912.html
blog.mozilla.org / security/2016/09/16/update-on-add-on-pinning-vulnerability
Third Party AdvisoryVDB Entry
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingThird Party AdvisoryVDB Entry
seclists.org / dailydave/2016/q3/51
Third Party Advisory
hackernoon.com / tor-browser-exposed-anti-privacy-implantation-at-mass-scale-bd68e9eb1e95
Technical Description
security.gentoo.org / glsa/201701-15
mozilla.org / security/advisories/mfsa2016-86
mozilla.org / security/advisories/mfsa2016-88
debian.org / security/2016/dsa-3674
mozilla.org / security/announce/2016/mfsa2016-85.html
Release Notes
oracle.com / technetwork/topics/security/linuxbulletinoct2016-3090545.html
securityfocus.com / bid/93049
securitytracker.com / id/1036852