CVE-2018-4174: Apple iPhone OS

Medium severity, CVSS 5.9. EPSS: 1.5% chance of exploitation in the next 30 days.

An issue was discovered in certain Apple products. iOS before 11.3 is affected. macOS before 10.13.4 is affected. The issue involves the "Mail" component. It allows man-in-the-middle attackers to read S/MIME encrypted messages by leveraging an inconsistency in the user interface.

Affected products

• Apple iPhone OS: before 11.3 (fixed in 11.3)
• Apple Mac OS X: before 10.13.4 (fixed in 10.13.4)

Published 2018-04-03. Last modified 2026-06-17.