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CVE-2016-5261

28
FAUCET Score

CVE-2016-5261 describes an integer overflow vulnerability in the WebSocketChannel class within Mozilla Firefox versions prior to 48.0 and Firefox ESR before 45.4. This flaw allows remote attackers to execute arbitrary code or cause a denial of service through memory corruption by sending crafted WebSocket packets that trigger incorrect buffer-resize operations. With a CVSS score of 8.8 (HIGH), this vulnerability is easily exploitable over the network with low attack complexity, requiring user interaction, and can lead to high impact on confidentiality, integrity, and availability. 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
<= 47.0.1CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
4.18%
Probability of exploitation in next 30 days
EPSS Percentile
89.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0418 is in the 90th percentile among its peer group of 14,848 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 (4)

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
mozillavendor investigatingvia nvd_reference
View patch

Vendor Advisories (1)

redhatCVE-2016-5261Important

Mozilla: Integer overflow and memory corruption in WebSocketChannel (MFSA 2016-75, MFSA 2016-86)

Sep 20, 2016

References

lists.opensuse.org / opensuse-security-announce/2016-08/msg00004.html
lists.opensuse.org / opensuse-security-announce/2016-08/msg00029.html
rhn.redhat.com / errata/RHSA-2016-1912.html
bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions Required
security.gentoo.org / glsa/201701-15
mozilla.org / security/advisories/mfsa2016-86
debian.org / security/2016/dsa-3674
mozilla.org / security/announce/2016/mfsa2016-75.html
Vendor Advisory
oracle.com / technetwork/topics/security/linuxbulletinoct2016-3090545.html
securityfocus.com / bid/92260
securitytracker.com / id/1036508
ubuntu.com / usn/USN-3044-1