What is CVE-2021-1788?

CVE-2021-1788 is a high-severity vulnerability in Apple iOS And Ipados, classified under Use After Free. CVSS score: 8.8/10. Published 2021-04-02.

How severe is CVE-2021-1788?

High severity. CVSS v3 base score is 8.8 out of 10.

Is CVE-2021-1788 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Use After Free in Apple iOS And Ipados

CVE-2021-1788

A use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.4, watchOS 7.3, iOS 14.4 and iPadOS 14.4, Safari 14.0.3. Processing maliciously crafted web content may lead to arbitrary code execution.

Vulnerability class: Use-After-Free

Published 2021-04-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.0th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: +0.000

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados
Apple Iphone OS
Apple macOS — versions unspecified
Apple Mac OS X — versions 10.14.6, 10.15.7
Apple Safari
Apple tvOS
Apple watchOS
Debian Linux — versions 10.0
Fedoraproject Fedora — versions 33

Weakness classification (CWE)

CWE-416 — Use After Free

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

support.apple.com/en-us/HT212147 (Release Notes, Vendor Advisory)
support.apple.com/en-us/HT212146 (Release Notes, Vendor Advisory)
support.apple.com/en-us/HT212148 (Release Notes, Vendor Advisory)
support.apple.com/en-us/HT212149 (Release Notes, Vendor Advisory)
support.apple.com/en-us/HT212152 (Release Notes, Vendor Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
www.debian.org/security/2021/dsa-4923 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2021-1788?: CVE-2021-1788 is a high-severity vulnerability in Apple iOS And Ipados, classified under Use After Free. CVSS score: 8.8/10. Published 2021-04-02.
How severe is CVE-2021-1788?: High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2021-1788 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.