CVE-2020-15659: Canonical Ubuntu Linux

High severity, CVSS 8.8. EPSS: 2.4% chance of exploitation in the next 30 days.

Mozilla developers and community members reported memory safety bugs present in Firefox 78 and Firefox ESR 78.0. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 79, Firefox ESR < 68.11, Firefox ESR < 78.1, Thunderbird < 68.11, and Thunderbird < 78.1.

Affected products

• Canonical Ubuntu Linux: version 16.04 only; version 18.04 only; version 20.04 only
• Mozilla Firefox: before 79.0 (fixed in 79.0)
• Mozilla Firefox ESR: before 68.11 (fixed in 68.11); from 78.0, before 78.1.0 (fixed in 78.1.0)
• Mozilla Thunderbird: before 68.11 (fixed in 68.11); from 78.0.1, before 78.1.0 (fixed in 78.1.0)
• Opensuse Leap: version 15.1 only; version 15.2 only

Published 2020-08-10. Last modified 2026-06-17.