What is CVE-2020-9958?

CVE-2020-9958 is a high-severity vulnerability in Apple iOS, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2020-10-16.

How severe is CVE-2020-9958?

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

Buffer overflow in Apple iOS

CVE-2020-9958

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 14.0 and iPadOS 14.0. An application may be able to cause unexpected system termination or write kernel memory.

Vulnerability class: Buffer Overflow

Published 2020-10-16 · 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: 0.011 (65.2th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: 0.000

Affected products

Apple iOS — versions unspecified
Apple Ipados
Apple Iphone OS

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

support.apple.com/HT211850 (Release Notes, Vendor Advisory)
seclists.org/fulldisclosure/2020/Nov/20 (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2020-9958?: CVE-2020-9958 is a high-severity vulnerability in Apple iOS, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2020-10-16.
How severe is CVE-2020-9958?: High severity. CVSS v3 base score is 7.8 out of 10.