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Fencer Vulns
high 7.8

CVE-2018-12379 json

When the Mozilla Updater opens a MAR format file which contains a very long item filename, an out-of-bounds write can be triggered, leading…

published 2018-10-18 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-4353

cvss
7.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

When the Mozilla Updater opens a MAR format file which contains a very long item filename, an out-of-bounds write can be triggered, leading to a potentially exploitable crash. This requires running the Mozilla Updater manually on the local system with the malicious MAR file in order to occur. This vulnerability affects Firefox < 62, Firefox ESR < 60.2, and Thunderbird < 60.2.1.

Patch / fix

  • Mozilla Firefox 62
  • Mozilla Firefox ESR 60.2
  • Mozilla Thunderbird 60.2.1
  • firefox-esr Debian 14, Debian 13, Debian 12 60.2.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:60.2.1-1

debian advisories DEBIAN-CVE-2018-12379

  • thunderbird RHEL 7 60.2.1-4.el7_5
  • thunderbird RHEL 6 60.2.1-5.el6
  • firefox RHEL 7 60.2.0-1.el7_5
  • firefox RHEL 6 60.2.0-1.el6

red hat advisories RHSA-2018:3458RHSA-2018:3403RHSA-2018:2692RHSA-2018:2693

  • apache2-mod_nss SLES 12 SP4, SLES 12 SP3, OpenStack Cloud 7 +7 more 1.0.14-19.6.3
  • mozilla-nss SLES 12 SP4, SLES 12 SP3, SLED 12 SP4 +12 more 3.36.4-58.15.3
  • mozilla-nspr SLES 12 SP4, SLES 12 SP3, SLED 12 SP4 +12 more 4.19-19.3.1
  • MozillaFirefox SLES 12 SP4, SLES 12 SP3, SLED 12 SP4 +12 more 60.2.2esr-109.46.1
  • MozillaFirefox-branding-SLE SLES 12 SP4, SLES 12 SP3, SLED 12 SP4 +10 more 60-32.3.1
  • MozillaFirefox SLE Module for Desktop Applications 15 60.2.0-3.10.1
  • MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 60-4.3.1

suse advisories SUSE-SU-2018:3591-2SUSE-SU-2018:3591-1SUSE-SU-2018:2890-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1

  • thunderbird Arch Linux 60.2.1-1

arch linux advisories AVG-782

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-2018-12379 updated cvss 7.8

Mozilla: Out-of-bounds write with malicious MAR file

  • Red Hat Enterprise Linux Client (v. 7) firefox 60.2.0-1.el7_5, thunderbird 60.2.1-4.el7_5 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.2.0-1.el7_5
    fixed: vendor fix RHSA-2018:2692
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.2.0-1.el6, thunderbird 60.2.1-5.el6 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.2.0-1.el6
    fixed: vendor fix RHSA-2018:2693
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.2.0-1.el7_5
    fixed: vendor fix RHSA-2018:2692
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) thunderbird 60.2.1-4.el7_5
    fixed: vendor fix RHSA-2018:3458
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.2.0-1.el6 Red Hat Enterprise Linux Server (v. 6) firefox 60.2.0-1.el6
    fixed: vendor fix RHSA-2018:2693
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.2.0-1.el7_5
    fixed: vendor fix RHSA-2018:2692
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.2.0-1.el6, thunderbird 60.2.1-5.el6
    fixed: vendor fix RHSA-2018:2693
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.2.0-1.el7_5, thunderbird 60.2.1-4.el7_5
    fixed: vendor fix RHSA-2018:2692
show 4 more
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.2.0-1.el6, thunderbird 60.2.1-5.el6
    fixed: vendor fix RHSA-2018:2693
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.2.0-1.el7_5, thunderbird 60.2.1-4.el7_5
    fixed: vendor fix RHSA-2018:2692
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.2.0-1.el6
    fixed: vendor fix RHSA-2018:2693
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.2.0-1.el7_5
    fixed: vendor fix RHSA-2018:2692

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

0.39% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 7.8 CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.6 AV:L/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

Classification

Weakness

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.