CVE-2018-5104: Canonical Ubuntu Linux

Critical severity, CVSS 9.8. EPSS: 7.2% chance of exploitation in the next 30 days.

A use-after-free vulnerability can occur during font face manipulation when a font face is freed while still in use, resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.6, Firefox ESR < 52.6, and Firefox < 58.

Affected products

• Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 17.10 only
• Debian Debian Linux: version 7.0 only; version 8.0 only; version 9.0 only
• Mozilla Firefox: before 58.0 (fixed in 58.0); before 52.6.0 (fixed in 52.6.0)
• Mozilla Thunderbird: before 52.6.0 (fixed in 52.6.0)
• 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 7.4 only
• Red Hat Enterprise Linux Server Eus: version 7.4 only; version 7.5 only
• Red Hat Enterprise Linux Workstation: version 6.0 only; version 7.0 only

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