What is CVE-2018-4400?

CVE-2018-4400 is a medium-severity vulnerability in Apple Iphone OS, classified under Improper Input Validation. CVSS score: 5.5/10. Published 2019-04-03.

How severe is CVE-2018-4400?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Improper input validation in Apple Iphone OS

CVE-2018-4400

A validation issue was addressed with improved logic. This issue affected versions prior to iOS 12.1, macOS Mojave 10.14.1, watchOS 5.1.

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

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

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.009 (58.6th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Apple Iphone OS
Apple Mac OS X
Apple watchOS
iOS, macOS, watchOS — versions Versions prior to: iOS 12.1, macOS Mojave 10.14.1, watchOS 5.1

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

support.apple.com/kb/HT209193 (Vendor Advisory)
support.apple.com/kb/HT209192 (Vendor Advisory)
support.apple.com/kb/HT209195 (Vendor Advisory)

Frequently asked questions

What is CVE-2018-4400?: CVE-2018-4400 is a medium-severity vulnerability in Apple Iphone OS, classified under Improper Input Validation. CVSS score: 5.5/10. Published 2019-04-03.
How severe is CVE-2018-4400?: Medium severity. CVSS v3 base score is 5.5 out of 10.