CVE-2018-12369: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 2.5% chance of exploitation in the next 30 days.

WebExtensions bundled with embedded experiments were not correctly checked for proper authorization. This allowed a malicious WebExtension to gain full browser permissions. This vulnerability affects Firefox ESR < 60.1 and Firefox < 61.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 17.10 only; version 18.04 only
• Mozilla Firefox: before 60.1.0 (fixed in 60.1.0); before 61.0 (fixed in 61.0)

Published 2018-10-18. Last modified 2026-06-17.