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Findings

CVE-2021-30663

Apple Multiple Products WebKit Integer Overflow Vulnerability

Published Sep 8, 2021 · updated Jun 16, 2026 · apple safari

Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer overflow vulnerability that leads to code execution 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.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 8, 2021 · Catalog

    Detected

    Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer overflow vulnerability that leads to code execution 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.

  2. Nov 3, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Nov 17, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer overflow vulnerability that leads to code execution 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.

Required action

Apply updates per vendor instructions.

CISA due date Nov 17, 2021

Affected

  • cpe apple/ipadosversion unspecified
  • cpe apple/iphone osversion unspecified
  • cpe apple/macosversion unspecified
  • cpe apple/safariversion unspecified
  • cpe apple/tvosversion unspecified
  • vendor Apple Multiple Productsversion unspecified

Sources

  • CISA KEVCVE-2021-30663

    Apple iOS, iPadOS, macOS, tvOS, and Safari WebKit contain an integer overflow vulnerability that leads to code execution 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.

    cisa.gov
  • CVE.orgCVE-2021-30663

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2021-30663

    30-day exploitation probability 3.5%

    first.org
  • NIST NVDCVE-2021-30663

    An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.

    nvd.nist.gov

References