An issue existed in the handling of encrypted Mail. This issue was addressed with improved isolation of MIME in Mail. This issue is fixed in macOS Mojave 10.14.4, Security Update 2019-002 High Sierra, Security Update 2019-002 Sierra. An attacker in a privileged network position may be able to intercept the contents of S/MIME-encrypted e-mail.
Severity
CVSS 3.1
6.5 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS
0.8% chance of exploitation in the next 30 days; higher than 55% of CVEs (scores of 2026-10-31)