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Fencer Vulns
high 8.8

CVE-2016-5261 json

Integer overflow in the WebSocketChannel class in the WebSockets subsystem in Mozilla Firefox before 48.0 and Firefox ESR < 45.4 allows rem…

published 2016-08-05 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6212

cvss
8.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.2%
EPSS 4.2% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

Integer overflow in the WebSocketChannel class in the WebSockets subsystem in Mozilla Firefox before 48.0 and Firefox ESR < 45.4 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted packets that trigger incorrect buffer-resize operations during buffering.

Patch / fix

  • firefox-esr Debian 14, Debian 13, Debian 12 45.4.0esr-1

debian advisories DEBIAN-CVE-2016-5261

  • firefox Ubuntu 14.04 LTS 48.0+build2-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 48.0+build2-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2016-5261

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox RHEL 5 45.4.0-1.el5_11
  • firefox RHEL 6 45.4.0-1.el6_8
  • firefox RHEL 7 45.4.0-1.el7_2

red hat advisories RHSA-2016:1912

  • MozillaFirefox SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +6 more 45.4.0esr-53.1
  • MozillaFirefox SLES for SAP 12 SP1, SLES for SAP 12, SLES 12-LTSS +3 more 45.4.0esr-81.1
  • MozillaFirefox SLES 11 SP2-LTSS 45.4.0esr-52.1

suse advisories SUSE-SU-2016:2513-1SUSE-SU-2016:2431-1SUSE-SU-2016:2434-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 50.1.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10071-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-5261 updated cvss 8.8

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

  • Red Hat Enterprise Linux (v. 5 server) firefox 45.4.0-1.el5_11 Red Hat Enterprise Linux Client (v. 7) firefox 45.4.0-1.el7_2 Red Hat Enterprise Linux Client Optional (v. 7) firefox 45.4.0-1.el7_2 Red Hat Enterprise Linux Desktop (v. 5 client) firefox 45.4.0-1.el5_11 Red Hat Enterprise Linux Desktop (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 45.4.0-1.el6_8
    +9 more products
    Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Server (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Server (v. 7) firefox 45.4.0-1.el7_2 Red Hat Enterprise Linux Server Optional (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Server Optional (v. 7) firefox 45.4.0-1.el7_2 Red Hat Enterprise Linux Workstation (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Workstation (v. 7) firefox 45.4.0-1.el7_2 Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 45.4.0-1.el6_8 Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 45.4.0-1.el7_2
    fixed: vendor fix RHSA-2016:1912
  • Red Hat Enterprise Linux 5 thunderbird Red Hat Enterprise Linux 6 thunderbird Red Hat Enterprise Linux 7 thunderbird
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

4.18% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.