CVE-2018-12373: Canonical Ubuntu Linux

Medium severity, CVSS 6.5. EPSS: 2.4% chance of exploitation in the next 30 days.

dDecrypted S/MIME parts hidden with CSS or the plaintext HTML tag can leak plaintext when included in a HTML reply/forward. This vulnerability affects Thunderbird < 52.9.

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 8.0 only; version 9.0 only
• Mozilla Thunderbird: before 52.9.0 (fixed in 52.9.0)
• Red Hat Enterprise Linux: version 6.0 only; version 7.0 only; version 7.5 only; version 7.6 only
• 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 Workstation: version 6.0 only; version 7.0 only

Published 2018-10-18. Last modified 2026-06-17.