CVE-2018-4221

Severity: high (CVSS 7.5 v3.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-06-08 · updated 2026-06-17
Weakness: CWE-200

Description

An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. The issue involves the "Security" component. It allows web sites to track users by leveraging the transmission of S/MIME client certificates.

Affected products

Apple Iphone Os: before 11.4 — fixed in 11.4
macOS: before 10.13.5 — fixed in 10.13.5

How to fix

Upgrade to a fixed version: Apple Iphone Os 11.4; macOS 10.13.5. Check the vendor advisory for mitigations.

References

http://www.securityfocus.com/bid/104897
http://www.securitytracker.com/id/1041027
https://support.apple.com/HT208848
https://support.apple.com/HT208849
http://www.securityfocus.com/bid/104897
http://www.securitytracker.com/id/1041027
https://support.apple.com/HT208848
https://support.apple.com/HT208849

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