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Fencer Intel
medium 6.5

CVE-2018-12396 json

A vulnerability where a WebExtension can run content scripts in disallowed contexts following navigation or other events.

published 2019-02-28 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-4370

cvss
6.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

A vulnerability where a WebExtension can run content scripts in disallowed contexts following navigation or other events. This allows for potential privilege escalation by the WebExtension on sites where content scripts should not be run. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.

Patch / fix

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

debian advisories DEBIAN-CVE-2018-12396

  • 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

ubuntu advisories UBUNTU-CVE-2018-12396

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

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

  • MozillaFirefox SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +13 more 60.3.0-109.50.2
  • 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-2018:3749-1SUSE-SU-2018:3656-1

  • 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 63.0-1

arch linux advisories AVG-787

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-2018-12396 updated cvss 6.1

Mozilla: WebExtension content scripts can execute in disallowed contexts

  • Red Hat Enterprise Linux Client (v. 7) firefox 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 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 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
    fixed: vendor fix RHSA-2018:3006
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.3.0-1.el7_5
    fixed: vendor fix RHSA-2018:3005
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.3.0-1.el6
    fixed: vendor fix RHSA-2018:3006
show 4 more
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 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 6 thunderbird Red Hat Enterprise Linux 7 thunderbird 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

2.27% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-732 Incorrect Permission Assignment for Critical Resource

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.