CVE-2018-5168: Canonical Ubuntu Linux

Medium severity, CVSS 5.3. EPSS: 2.4% chance of exploitation in the next 30 days.

Sites can bypass security checks on permissions to install lightweight themes by manipulating the "baseURI" property of the theme element. This could allow a malicious site to install a theme without user interaction which could contain offensive or embarrassing images. This vulnerability affects Thunderbird < 52.8, Thunderbird ESR < 52.8, Firefox < 60, and Firefox ESR < 52.8.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 17.10 only; version 18.04 only
• Debian Debian Linux: version 7.0 only; version 8.0 only; version 9.0 only
• Mozilla Firefox: before 52.8.0 (fixed in 52.8.0); before 60.0 (fixed in 60.0)
• Mozilla Thunderbird: before 52.8.0 (fixed in 52.8.0)
• Mozilla Thunderbird ESR: before 52.8.0 (fixed in 52.8.0)
• Red Hat Enterprise Linux Desktop: version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Server: version 6.0 only; version 7.0 only
• Red Hat Enterprise Linux Server Aus: version 7.6 only
• Red Hat Enterprise Linux Server Eus: version 7.5 only; version 7.6 only
• Red Hat Enterprise Linux Server Tus: version 7.6 only
• Red Hat Enterprise Linux Workstation: version 6.0 only; version 7.0 only

Published 2018-06-11. Last modified 2026-06-17.