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Findings

CVE-2021-1871

Apple iOS, iPadOS, and macOS WebKit Remote Code Execution Vulnerability

Published Apr 2, 2021 · updated Jun 16, 2026 · apple ipados

A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

Timeline

Detection, updates, and resolution for this record.

  1. Apr 2, 2021 · Catalog

    Detected

    A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

  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

    A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..

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/mac os xversion unspecified
  • cpe apple/mac os x10.15.7
  • cpe apple/macosversion unspecified
  • cpe debian/debian linux10.0
  • cpe fedoraproject/fedora33
  • vendor Apple iOS, iPadOS, and macOSversion unspecified

Sources

  • CISA KEVCVE-2021-1871

    Apple iOS, iPadOS, and macOS WebKit contain an unspecified logic vulnerability that allows a remote attacker to execute code. 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-2021-1871

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2021-1871

    30-day exploitation probability 7.0%

    first.org
  • NIST NVDCVE-2021-1871

    A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a re

    nvd.nist.gov

References