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Fencer Intel
critical 9.8

CVE-2016-5256 json

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 49.0 allow remote attackers to cause a denial of servi…

published 2016-09-22 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-6207

cvss
9.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.8%
EPSS 3.8% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 49.0 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.

Patch / fix

  • firefox Ubuntu 14.04 LTS 49.0+build4-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 49.0+build4-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2016-5256

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-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

  • firefox Arch Linux 49.0-1

arch linux advisories AVG-24

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-2016-5256 updated cvss 9.8

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

  • Red Hat Enterprise Linux 5 firefox, thunderbird Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 firefox, 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

3.84% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 9.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/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-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Intel 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.