What’s Vulnerable › Vulnerabilities

CVE-2018-12396

• Severity: medium (CVSS 6.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-02-28 · updated 2026-06-17
• Weakness: CWE-732

Description

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.

Affected products

• Canonical Ubuntu Linux: 14.04, 16.04, 18.04, 18.10
• Debian Linux: 8.0, 9.0
• Mozilla Firefox: before 63.0 — fixed in 63.0
• Mozilla Firefox ESR: before 60.3 — fixed in 60.3
• RedHat Enterprise Linux Desktop: 6.0, 7.0
• RedHat Enterprise Linux Server: 6.0, 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, 7.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 63.0; Mozilla Firefox ESR 60.3. Check the vendor advisory for mitigations.

References

• http://www.securityfocus.com/bid/105718
• http://www.securitytracker.com/id/1041944
• https://access.redhat.com/errata/RHSA-2018:3005
• https://access.redhat.com/errata/RHSA-2018:3006
• https://bugzilla.mozilla.org/show_bug.cgi?id=1483602
• https://lists.debian.org/debian-lts-announce/2018/11/msg00008.html
• https://security.gentoo.org/glsa/201811-04
• https://usn.ubuntu.com/3801-1/
• https://www.debian.org/security/2018/dsa-4324
• https://www.mozilla.org/security/advisories/mfsa2018-26/
• https://www.mozilla.org/security/advisories/mfsa2018-27/
• http://www.securityfocus.com/bid/105718

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