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Fencer Vulns
high 8.1

CVE-2018-12386 in the critical feed json

A vulnerability in register allocation in JavaScript can lead to type confusion, allowing for an arbitrary read and write.

published 2018-10-18 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-4360

cvss
8.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
13.5%
EPSS 13.5% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

A vulnerability in register allocation in JavaScript can lead to type confusion, allowing for an arbitrary read and write. This leads to remote code execution inside the sandboxed content process when triggered. This vulnerability affects Firefox ESR < 60.2.2 and Firefox < 62.0.3.

Patch / fix

  • Mozilla Firefox ESR 60.2.2
  • Mozilla Firefox 62.0.3
  • firefox-esr Debian 14, Debian 13, Debian 12 60.2.2esr-1

debian advisories DEBIAN-CVE-2018-12386

  • firefox Ubuntu 14.04 LTS 62.0.3+build1-0ubuntu0.14.04.2
  • firefox Ubuntu 16.04 LTS 62.0.3+build1-0ubuntu0.16.04.2
  • firefox Ubuntu 18.04 LTS 62.0.3+build1-0ubuntu0.18.04.1
  • 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-2018-12386

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 6 60.2.2-1.el6
  • firefox RHEL 7 60.2.2-1.el7_5

red hat advisories RHSA-2018:2881RHSA-2018:2884

  • 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 60.2.2-3.13.3
  • MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 60-4.5.3

suse advisories SUSE-SU-2018:3591-2SUSE-SU-2018:3591-1SUSE-SU-2018:3476-1

  • 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

  • firefox Arch Linux 62.0.3-1

arch linux advisories AVG-775

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-2018-12386 updated cvss 8.8

Mozilla: type confusion in JavaScript

  • Red Hat Enterprise Linux Client (v. 7) firefox 60.2.2-1.el7_5 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.2.2-1.el6 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.2.2-1.el6
    fixed: vendor fix RHSA-2018:2881
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.2.2-1.el6 Red Hat Enterprise Linux Server (v. 6) firefox 60.2.2-1.el6
    fixed: vendor fix RHSA-2018:2881
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.2.2-1.el6
    fixed: vendor fix RHSA-2018:2881
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.2.2-1.el6
    fixed: vendor fix RHSA-2018:2881
show 4 more
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.2.2-1.el6
    fixed: vendor fix RHSA-2018:2881
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.2.2-1.el7_5
    fixed: vendor fix RHSA-2018:2884
  • 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

13.52% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1493900 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 8.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:P/A:N

Affected products

  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-704 Incorrect Type Conversion or Cast

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.