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Actively exploited

CVE-2023-28204 Apple Multiple Products WebKit Out-of-Bounds Read Vulnerability

Apple iOS, iPadOS, macOS, tvOS, watchOS, and Safari WebKit contain an out-of-bounds read vulnerability that may disclose sensitive information when processing maliciously crafted web content. This vulnerability could impact HTML parsers that use WebKit, including but not limited to Apple Safari and non-Apple products which rely on WebKit for HTML processing.

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 22 May 2023.
  • Rated Medium severity (CVSS 6.5, scored by CISA).
  • It has been in the catalogue for 1,264 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

An out-of-bounds read was addressed with improved input validation. This issue is fixed in watchOS 9.5, tvOS 16.5, macOS Ventura 13.4, iOS 15.7.6 and iPadOS 15.7.6, Safari 16.5, iOS 16.5 and iPadOS 16.5. Processing web content may disclose sensitive information. Apple is aware of a report that this issue may have been actively exploited.

Affected Versions

ProductVersions
Apple macOSunspecified to before 13.4
Apple Safariunspecified to before 16.5
Apple watchOSunspecified to before 9.5
Apple iOS and iPadOSunspecified to before 15.7
Apple iOS and iPadOSunspecified to before 16.5
Apple tvOSunspecified to before 16.5

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 EssentialsCyber Essentials requires high and critical updates (CVSS 7.0 or above) within 14 days of release. Treat any exploited flaw the same way.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 12 Jun 2023 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

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2023-28204 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2023-28204
  3. CVE record: CVE-2023-28204
  4. FIRST EPSS
  5. support.apple.com/HT213757, https://support.apple.com/HT213758, https://support.apple.com/HT213761,
  6. support.apple.com/en-us/HT213758
  7. support.apple.com/en-us/HT213762
  8. support.apple.com/en-us/HT213764
  9. support.apple.com/en-us/HT213765
  10. support.apple.com/en-us/HT213757
  11. support.apple.com/en-us/HT213761
  12. security.gentoo.org/glsa/202401-04