CVE-2018-5178: Canonical Ubuntu Linux

High severity, CVSS 8.1. EPSS: 5% chance of exploitation in the next 30 days.

A buffer overflow was found during UTF8 to Unicode string conversion within JavaScript with extremely large amounts of data. This vulnerability requires the use of a malicious or vulnerable legacy extension in order to occur. This vulnerability affects Thunderbird ESR < 52.8, Thunderbird < 52.8, 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)
• 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.