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Actively exploited

CVE-2021-1789 Apple Multiple Products Type Confusion Vulnerability

A type confusion issue affecting multiple Apple products allows processing of maliciously crafted web content, leading to arbitrary code execution.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 4 May 2022.
  • Rated High severity (CVSS 8.8, scored by CISA).
  • It has been in the catalogue for 1,647 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

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.

Affected Versions

ProductVersions
Apple iOS and iPadOSunspecified to before 14.4
Apple macOSunspecified to before 11.2
Apple macOSunspecified to before 7.3
Apple macOSunspecified to before 14.4
Apple macOSunspecified to before 14.0

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Apple Multiple Products. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 25 May 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited Apple Flaws

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CVE-2024-27834Apple Multiple Products Improper Authentication VulnerabilityAdded 4 Nov 2026CVE-2026-86950Apple Multiple Products Out-of-Bounds Write VulnerabilityAdded 29 Sep 2026CVE-2026-65400Apple macOS Improper Authentication VulnerabilityAdded 18 Aug 2026CVE-2025-43510Apple Multiple Products Improper Locking VulnerabilityAdded 20 Mar 2026CVE-2025-43520Apple Multiple Products Classic Buffer Overflow VulnerabilityAdded 20 Mar 2026CVE-2025-31277Apple Multiple Products Buffer Overflow VulnerabilityAdded 20 Mar 2026

All 96 exploited Apple vulnerabilities

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2021-1789
  3. CVE record: CVE-2021-1789
  4. FIRST EPSS
  5. support.apple.com/en-us/HT212147
  6. support.apple.com/en-us/HT212146
  7. support.apple.com/en-us/HT212148
  8. support.apple.com/en-us/HT212149
  9. support.apple.com/en-us/HT212152
  10. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS
  11. lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN6ZOD62CTO
  12. security.gentoo.org/glsa/202104-03