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TI-2021-01531 Aliases CVE-2021-1821GHSA-p9hx-m56p-r6wc

Apple macOS: Visiting a maliciously crafted webpage may lead to a system denial of service

Priority LOW 30Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA.

Summary

A logic issue was addressed with improved state management. This issue is fixed in watchOS 7.6, macOS Big Sur 11.5. Visiting a maliciously crafted webpage may lead to a system denial of service.

Why it matters now

EPSS 0.00658 51st percentileScored 2026-11-07
Fix Fixed macOS (Apple): 11.5, 7.6

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
ApplemacOSbefore 11.511.5Patch availableCNA
ApplemacOSbefore 7.67.6Patch availableCNA
  • macOS VendorApple Affected before 11.5 Fixed in 11.5 Patch available CNA
  • macOS VendorApple Affected before 7.6 Fixed in 7.6 Patch available CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*before 11.5VulnerableApple
cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:*before 7.6VulnerableApple
  • cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:* Versions before 11.5 Vulnerable ·Apple
  • cpe:2.3:o:apple:watchos:*:*:*:*:*:*:*:* Versions before 7.6 Vulnerable ·Apple

Remediation

  • Fix · CNA macOS (Apple) Fixed in 11.5
  • Fix · CNA macOS (Apple) Fixed in 7.6

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Apple macOS 11.5

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2021-11191 Apple macOS: A malicious application may be able to access data about the accounts the…Priority LOW 26
    Show all 2 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1821
  2. 2026-10-03 Alias added: GHSA-p9hx-m56p-r6wc
  3. 2026-10-09 EPSS moved to the 50th–90th percentile

References

Advisory 2

  • TI-2026-46583 Improper authentication in Apple macOS KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-28008 Out-of-bounds write in Apple iOS and iPadOS KEVCVSS 3.1CRITICAL 10.0
  • TI-2025-22441 Apple iOS and iPadOS: An attacker with arbitrary read and write capability may be able to… KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-22440 Memory corruption in Apple iOS and iPadOS KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-17951 Out-of-bounds write in Apple Safari KEVCVSS 3.1CRITICAL 10.0
  • TI-2025-17847 Use after free in Apple iOS and iPadOS KEVCVSS 3.1CRITICAL 10.0
See all 3490 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences