CVE-2020-9991

7.5 highEPSS 2.8%

This issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, iOS 14.0 and iPadOS 14.0, iCloud for Windows 7.21, tvOS 14.0. A remote attacker may be able to cause a denial of service.

Severity

CVSS 3.1

7.5 high

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 2.8% chance of exploitation in the next 30 days; higher than 86% of CVEs (scores of 2026-10-31)
Published: 2020-12-08
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

apple:icloud
apple:ipados
apple:iphone_os
apple:mac_os_x
apple:tvos
apple:watchos

References

http://seclists.org/fulldisclosure/2020/Dec/32
https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
https://support.apple.com/en-us/HT211843
https://support.apple.com/en-us/HT211844
https://support.apple.com/en-us/HT211847

Check your stack JSON