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Fencer Vulns
high 7.5

CVE-2018-12393 json

A potential vulnerability was found in 32-bit builds where an integer overflow during the conversion of scripts to an internal UTF-16 repre…

published 2019-02-28 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-4367

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.9%
EPSS 3.9% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

A potential vulnerability was found in 32-bit builds where an integer overflow during the conversion of scripts to an internal UTF-16 representation could result in allocating a buffer too small for the conversion. This leads to a possible out-of-bounds write. *Note: 64-bit builds are not vulnerable to this issue.*. This vulnerability affects Firefox < 63, Firefox ESR < 60.3, and Thunderbird < 60.3.

Patch / fix

  • Mozilla Firefox 63
  • Mozilla Firefox ESR 60.3
  • Mozilla Thunderbird 60.3
  • firefox-esr Debian 14, Debian 13, Debian 12 60.3.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:60.3.0-1

debian advisories DEBIAN-CVE-2018-12393

  • firefox Ubuntu 14.04 LTS 63.0+build2-0ubuntu0.14.04.2
  • firefox Ubuntu 16.04 LTS 63.0+build2-0ubuntu0.16.04.2
  • firefox Ubuntu 18.04 LTS 63.0+build2-0ubuntu0.18.04.2
  • thunderbird Ubuntu 14.04 LTS 1:60.4.0+build2-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:60.4.0+build2-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:60.4.0+build2-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2018-12393

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

  • thunderbird RHEL 7 60.3.0-1.el7_5
  • thunderbird RHEL 6 60.3.0-1.el6
  • firefox RHEL 6 60.3.0-1.el6
  • firefox RHEL 7 60.3.0-1.el7_5

red hat advisories RHSA-2018:3532RHSA-2018:3531RHSA-2018:3006RHSA-2018:3005

  • MozillaFirefox SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +13 more 60.3.0-109.50.2
  • MozillaThunderbird SLE Workstation Extension 15 60.3.0-3.17.2
  • MozillaFirefox SLE Module for Desktop Applications 15 60.3.0-3.17.1

suse advisories SUSE-SU-2018:3749-3SUSE-SU-2018:3749-2SUSE-SU-2018:3769-1SUSE-SU-2018:3749-1SUSE-SU-2018:3656-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
  • MozillaThunderbird Package Hub 12 60.3.0-74.2

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2024:10601-1openSUSE-SU-2018:3687-1

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-2018-12393 updated cvss 7.5

Mozilla: Integer overflow during Unicode conversion while loading JavaScript

  • Red Hat Enterprise Linux Client (v. 7) firefox 60.3.0-1.el7_5, thunderbird 60.3.0-1.el7_5 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.3.0-1.el6, thunderbird 60.3.0-1.el6 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) thunderbird 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3532
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.3.0-1.el6 Red Hat Enterprise Linux Server (v. 6) firefox 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.3.0-1.el6, thunderbird 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.3.0-1.el7_5, thunderbird 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
show 5 more
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.3.0-1.el6, thunderbird 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.3.0-1.el7_5, thunderbird 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux 8 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

3.92% 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 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/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.