What is CVE-2021-1805?

CVE-2021-1805 is a high-severity vulnerability in Apple macOS, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-04-02.

How severe is CVE-2021-1805?

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

Buffer overflow in Apple macOS

CVE-2021-1805

An out-of-bounds write was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.2.1, macOS Catalina 10.15.7 Supplemental Update, macOS Mojave 10.14.6 Security Update 2021-002. An application may be able to execute arbitrary code with kernel privileges.

Vulnerability class: Buffer Overflow

Published 2021-04-02 · 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 (65.5th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.5% 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 macOS — versions unspecified
Apple Mac OS X — versions 10.14.6, 10.15.7

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

support.apple.com/en-us/HT212177 (Vendor Advisory)
support.apple.com/kb/HT212327 (Vendor Advisory)
seclists.org/fulldisclosure/2021/Apr/54 (mailing-list, Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2021-1805?: CVE-2021-1805 is a high-severity vulnerability in Apple macOS, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2021-04-02.
How severe is CVE-2021-1805?: High severity. CVSS v3 base score is 7.8 out of 10.