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CVE-2016-5256

31
FAUCET Score

CVE-2016-5256 describes multiple unspecified vulnerabilities within the browser engine of Mozilla Firefox, affecting versions prior to 49.0. These flaws could be remotely triggered, leading to a denial of service through memory corruption and application crashes, or potentially enabling arbitrary code execution. With a CVSS score of 9.8 (CRITICAL), this vulnerability is easily exploitable over a network with low attack complexity, posing high impacts to confidentiality, integrity, and availability. While no public exploit code (Metasploit, Nuclei, ExploitDB) is currently available and it is not listed on the KEV catalog, its EPSS score and community discussion indicate some level of awareness, and it received media coverage upon its disclosure.

Impacted Technologies

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

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.84%
Probability of exploitation in next 30 days
EPSS Percentile
89.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0384 is in the 82nd percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

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

Remediation

Vendor Patches (1)

mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2016-5256Critical

Mozilla: Memory safety bugs fixed in Firefox 49 (MFSA 2016-85)

Sep 20, 2016

References

bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
bugzilla.mozilla.org / show_bug.cgi
Issue Tracking
security.gentoo.org / glsa/201701-15
mozilla.org / security/announce/2016/mfsa2016-85.html
Vendor Advisory
securityfocus.com / bid/93052
securitytracker.com / id/1036852