CVE-2014-1559: Mozilla Firefox

Medium severity, CVSS 4.3. EPSS: 1.7% chance of exploitation in the next 30 days.

Mozilla Firefox before 31.0 and Thunderbird before 31.0 allow remote attackers to cause a denial of service (X.509 certificate parsing outage) via a crafted certificate that does not use UTF-8 character encoding in a required context, a different vulnerability than CVE-2014-1558.

Affected products

• Mozilla Firefox: up to and including 30.0
• Mozilla Thunderbird: up to and including 24.7; version 24.0 only; version 24.0.1 only; version 24.1 only; version 24.1.1 only; version 24.2 only; …

Published 2014-07-23. Last modified 2026-06-17.