What is CVE-2020-9966?

CVE-2020-9966 is a high-severity vulnerability in Apple iOS And Ipados, classified under Out-of-bounds Read. CVSS score: 7.8/10. Published 2020-12-08.

How severe is CVE-2020-9966?

High severity. CVSS v3 base score is 7.8 out of 10.

Out-of-bounds Read in Apple iOS And Ipados

CVE-2020-9966

An out-of-bounds read was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0. An application may be able to execute arbitrary code with kernel privileges.

Vulnerability class: Buffer Overflow

Published 2020-12-08 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.013 (68.6th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 68.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Apple iOS And Ipados — versions unspecified
Apple Ipados
Apple Iphone OS
Apple macOS — versions unspecified
Apple Mac OS X
Apple tvOS — versions unspecified
Apple watchOS — versions unspecified

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

support.apple.com/en-us/HT211843 (Vendor Advisory)
support.apple.com/en-us/HT211850 (Vendor Advisory)
support.apple.com/en-us/HT211844 (Vendor Advisory)
support.apple.com/en-us/HT211931 (Vendor Advisory)
seclists.org/fulldisclosure/2020/Dec/32 (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2020-9966?: CVE-2020-9966 is a high-severity vulnerability in Apple iOS And Ipados, classified under Out-of-bounds Read. CVSS score: 7.8/10. Published 2020-12-08.
How severe is CVE-2020-9966?: High severity. CVSS v3 base score is 7.8 out of 10.