CVE-2018-12396: Medium severity Mozilla Firefox vulnerability

Published Oct 23, 2018
·
Updated

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.

Affected Software

21 affected componentsFixes available
Mozilla Firefox<63
63
Mozilla Firefox ESR<60.3
60.3
Mozilla Firefox<63.0
Mozilla Firefox ESR<60.3
Debian Debian Linux=8.0
Debian Debian Linux=9.0
Canonical Ubuntu Linux=14.04
Canonical Ubuntu Linux=16.04
Canonical Ubuntu Linux=18.04
Canonical Ubuntu Linux=18.10
redhat Enterprise Linux Desktop=6.0
redhat Enterprise Linux Desktop=7.0
redhat Enterprise Linux Server=6.0
redhat Enterprise Linux Server=7.0
redhat Enterprise Linux Server Aus=7.6
redhat Enterprise Linux Server Eus=7.6
redhat Enterprise Linux Server Tus=7.6
redhat Enterprise Linux Workstation=6.0
redhat Enterprise Linux Workstation=7.0
debian/firefox
149.0.2-1
debian/firefox-esr
115.14.0esr-1~deb11u1140.9.1esr-1~deb11u1128.14.0esr-1~deb12u1140.9.1esr-1~deb12u1140.8.0esr-1~deb13u1140.9.1esr-1~deb13u1140.9.1esr-1

Event History

Oct 23, 2018
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Red Hat·10:08 PM
DescriptionSeverityAffected Software
Feb 28, 2019
CVE Published
via MITRE·06:00 PM
Data Sourced
via MITRE·06:00 PM
DescriptionWeakness
Jan 11, 2024
Data Sourced
via Launchpad·10:49 PM
Description
Nov 30, 2025
Data Sourced
via Ubuntu·06:17 PM
RemedyDescriptionSeverityAffected Software
Apr 14, 2026
Data Sourced
via Debian·05:01 PM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is CVE-2018-12396?

CVE-2018-12396 is a vulnerability where a WebExtension can run content scripts in disallowed contexts following navigation or other events, potentially allowing for privilege escalation.

2

Which software versions are affected by CVE-2018-12396?

Firefox ESR < 60.3 and Firefox < 63.0 are affected by CVE-2018-12396.

3

What is the severity of CVE-2018-12396?

CVE-2018-12396 has a severity rating of 6.5, which is considered medium.

4

How can I fix CVE-2018-12396?

To fix CVE-2018-12396, update Firefox ESR to version 60.3 or later, or update Firefox to version 63.0 or later.

5

Where can I find more information about CVE-2018-12396?

You can find more information about CVE-2018-12396 on the following references: [Mozilla Bugzilla](https://bugzilla.mozilla.org/show_bug.cgi?id=1483602), [Mozilla Security Advisory](https://www.mozilla.org/en-US/security/advisories/mfsa2018-27/), [CVE Mitre](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-12396).

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203