CVE-2019-11759: Canonical Ubuntu Linux

High severity, CVSS 8.8. EPSS: 1.8% chance of exploitation in the next 30 days.

An attacker could have caused 4 bytes of HMAC output to be written past the end of a buffer stored on the stack. This could be used by an attacker to execute arbitrary code or more likely lead to a crash. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.

Affected products

• Canonical Ubuntu Linux: version 16.04 only
• Mozilla Firefox: before 70.0 (fixed in 70.0)
• Mozilla Firefox ESR: before 68.2 (fixed in 68.2)
• Mozilla Thunderbird: before 68.2 (fixed in 68.2)

Published 2020-01-08. Last modified 2026-06-17.