CVE-2021-1789: Apple Multiple Products Type Confusion Vulnerability

Q: How do I fix CVE-2021-1789?

ipados: upgrade to 14.4; iphone os: upgrade to 14.4; mac os x: upgrade to 10.14.6, 10.15.7. Exact commands for each OS are on this page.

Q: Is CVE-2021-1789 being exploited?

Yes. CVE-2021-1789 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2021-1789 affect?

CVE-2021-1789 affects ipados, iphone os, mac os x. Severity is high (CVSS 8.8). A type confusion issue was addressed with improved state handling. 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.

Q: How urgent is CVE-2021-1789?

Priority 80/100. High severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV)

Patch now

HIGH 8.8EXPLOITEDUPGRADEUPGRADEUPGRADE

CVE-2021-1789 is a high-severity flaw (CVSS 8.8) affecting ipados, iphone os, mac os x, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A type confusion issue was addressed with improved state handling. 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.

Why this priority

High severity
EPSS top 3%: very likely to be exploited
Exploited in the wild (CISA KEV)

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	14.0% (top 3%)
CISA exploited list	Yes, fix due 2022-05-25
Weakness	CWE-843
Published	2021-04-02
Last modified	2026-06-17

Publisher (CNA): Apple Inc. · Vendor: apple

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-04-02 18:15 UTCPublished CVE record published
2022-05-04Exploited Added to the CISA Known Exploited Vulnerabilities list
2022-05-25Deadline CISA due date for US federal agencies to patch
2026-06-17 03:32 UTCUpdated Record last modified

apple ipados UPGRADE

Affected: < 14.4

Fixed in: 14.4

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apple iphone os UPGRADE

Affected: < 14.4

Fixed in: 14.4

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apple mac os x UPGRADE

Affected: >= 10.14 and < 10.14.6 · >= 10.15 and < 10.15.7 · 10.14.6 · 10.14.6 security_update_2019-004 · 10.14.6 security_update_2019-005 · 10.14.6 security_update_2019-006 · 10.14.6 security_update_2019-007 · 10.14.6 security_update_2020-001

Fixed in: 10.14.6, 10.15.7

Safe to downgrade to: a release before 10.14

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apple macos UPGRADE

Affected: >= 11.0 and < 11.2

Fixed in: 11.2

Safe to downgrade to: a release before 11.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apple tvos UPGRADE

Affected: < 14.4

Fixed in: 14.4

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

apple watchos UPGRADE

Affected: < 7.3

Fixed in: 7.3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · python-dtoc · FIXED · 0.1.0-1.fc46 · FEDORA-2026-e4734649a1 · source

sudo dnf upgrade --advisory=FEDORA-2026-e4734649a1

Fedora ELN · parallel · FIXED · 20261022-1.eln159 · FEDORA-2026-6d961c0286 · source

sudo dnf upgrade --advisory=FEDORA-2026-6d961c0286

Ubuntu 20.04 · webkit2gtk · FIXED · 2.30.6-0ubuntu0.20.04.1

sudo apt update && sudo apt install --only-upgrade webkit2gtk dpkg --compare-versions "$(dpkg-query -W -f='${Version}' webkit2gtk)" ge "2.30.6-0ubuntu0.20.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · webkit2gtk · FIXED · 2.32.0-1ubuntu3

sudo apt update && sudo apt install --only-upgrade webkit2gtk dpkg --compare-versions "$(dpkg-query -W -f='${Version}' webkit2gtk)" ge "2.32.0-1ubuntu3" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · webkit2gtk · FIXED · 2.32.0-1ubuntu3

sudo apt update && sudo apt install --only-upgrade webkit2gtk dpkg --compare-versions "$(dpkg-query -W -f='${Version}' webkit2gtk)" ge "2.32.0-1ubuntu3" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · webkit2gtk · FIXED · 2.30.6-1

sudo apt update && sudo apt install --only-upgrade webkit2gtk dpkg --compare-versions "$(dpkg-query -W -f='${Version}' webkit2gtk)" ge "2.30.6-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · webkit2gtk · FIXED · 2.30.6-1

sudo apt update && sudo apt install --only-upgrade webkit2gtk dpkg --compare-versions "$(dpkg-query -W -f='${Version}' webkit2gtk)" ge "2.30.6-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · wpewebkit · FIXED · 2.30.6-1

sudo apt update && sudo apt install --only-upgrade wpewebkit dpkg --compare-versions "$(dpkg-query -W -f='${Version}' wpewebkit)" ge "2.30.6-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · wpewebkit · FIXED · 2.30.6-1

sudo apt update && sudo apt install --only-upgrade wpewebkit dpkg --compare-versions "$(dpkg-query -W -f='${Version}' wpewebkit)" ge "2.30.6-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 7 Extended Lifecycle Support · webkitgtk4 · FIXED · webkitgtk4-2.48.3-2.el7_9

sudo dnf upgrade --advisory=RHSA-2025:10364 rpm -q webkitgtk4

RHEL 8 · webkit2gtk3 · FIXED · webkit2gtk3-2.32.3-2.el8

sudo dnf upgrade --advisory=RHSA-2021:4381 rpm -q webkit2gtk3

RHEL 6 · webkitgtk · DEFERRED

RHEL 7 · webkitgtk3 · DEFERRED

RHEL 9 · webkit2gtk3 · NOT AFFECTED

Alpine 3.20 · webkit2gtk · FIXED · webkit2gtk-2.30.6-r0

apk add --upgrade webkit2gtk apk info -v webkit2gtk

Amazon Linux 2 · see advisory · FIXED · ALAS2-2023-2088 · source

sudo yum update --advisory=ALAS2-2023-2088

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-1789?

ipados: upgrade to 14.4; iphone os: upgrade to 14.4; mac os x: upgrade to 10.14.6, 10.15.7. Exact commands for each OS are on this page.

Is CVE-2021-1789 being exploited?

Yes. CVE-2021-1789 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2021-1789 affect?

CVE-2021-1789 affects ipados, iphone os, mac os x. Severity is high (CVSS 8.8). A type confusion issue was addressed with improved state handling. 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.

How urgent is CVE-2021-1789?

Priority 80/100. High severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV)

Software pages

iOS vulnerabilities · macOS vulnerabilities · Safari vulnerabilities · Apple Safari and WebKit vulnerabilities · iPadOS vulnerabilities · watchOS vulnerabilities

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References

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