What is CVE-2018-4321?

CVE-2018-4321 is a medium-severity vulnerability in Apple Iphone OS, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2019-04-03.

How severe is CVE-2018-4321?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Improper input validation in Apple Iphone OS

CVE-2018-4321

A validation issue existed in the entitlement verification. This issue was addressed with improved validation of the process entitlement. This issue affected versions prior to iOS 12, macOS Mojave 10.14, tvOS 12.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2019-04-03 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.013 (69.7th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 69.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Apple Iphone OS
Apple Mac OS X
Apple tvOS
iOS, macOS, tvOS — versions Versions prior to: iOS 12, macOS Mojave 10.14, tvOS 12

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

support.apple.com/kb/HT209107 (Vendor Advisory)
support.apple.com/kb/HT209106 (Vendor Advisory)
support.apple.com/kb/HT209139 (Vendor Advisory)

Frequently asked questions

What is CVE-2018-4321?: CVE-2018-4321 is a medium-severity vulnerability in Apple Iphone OS, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2019-04-03.
How severe is CVE-2018-4321?: Medium severity. CVSS v3 base score is 5.3 out of 10.