CVE-2020-9991

HIGHNVD 7.57.5—

7.5

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.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 84.5%
KEV: Not listed

Published

December 8, 2020

Last Modified

November 21, 2024

References (16)

product-security@applehttp://seclists.org/fulldisclosure/2020/Dec/32
product-security@applehttps://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
product-security@applehttps://support.apple.com/en-us/HT211843
product-security@applehttps://support.apple.com/en-us/HT211844
product-security@applehttps://support.apple.com/en-us/HT211847
product-security@applehttps://support.apple.com/en-us/HT211850
product-security@applehttps://support.apple.com/en-us/HT211931
product-security@applehttps://support.apple.com/kb/HT211846
af854a3a-2127-422b-91ae-364da2661108http://seclists.org/fulldisclosure/2020/Dec/32
af854a3a-2127-422b-91ae-364da2661108https://lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
af854a3a-2127-422b-91ae-364da2661108https://support.apple.com/en-us/HT211843
af854a3a-2127-422b-91ae-364da2661108https://support.apple.com/en-us/HT211844
af854a3a-2127-422b-91ae-364da2661108https://support.apple.com/en-us/HT211847
af854a3a-2127-422b-91ae-364da2661108https://support.apple.com/en-us/HT211850
af854a3a-2127-422b-91ae-364da2661108https://support.apple.com/en-us/HT211931

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-08 14:15 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 06:08 UTCEPSS rescore
2026-06-05 06:08 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore
2026-05-29 13:42 UTCEPSS rescore

Frequently asked(5)

What is CVE-2020-9991?

CVE-2020-9991 is a high vulnerability published on December 8, 2020. 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.

When was CVE-2020-9991 disclosed?

CVE-2020-9991 was first published in the National Vulnerability Database on December 8, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2020-9991 actively exploited?

CVE-2020-9991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 84.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2020-9991?

CVE-2020-9991 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2020-9991?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-9991, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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CVE-2020-9991

📅 Published

🔄 Last Modified

🔗 References (16)