What is CVE-2019-8766?

CVE-2019-8766 is a high-severity vulnerability in Apple Icloud, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2019-12-18.

How severe is CVE-2019-8766?

High severity. CVSS v3 base score is 8.8 out of 10.

Buffer overflow in Apple Icloud

CVE-2019-8766

Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in watchOS 6.1, iCloud for Windows 11.0. Processing maliciously crafted web content may lead to arbitrary code execution.

Vulnerability class: Buffer Overflow

Published 2019-12-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.6th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Apple Icloud
Apple Icloud For Windows — versions unspecified
Apple watchOS — versions unspecified

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

support.apple.com/HT210724 (Vendor Advisory)
support.apple.com/HT210727 (Vendor Advisory)
security.gentoo.org/glsa/202003-22 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2019-8766?: CVE-2019-8766 is a high-severity vulnerability in Apple Icloud, classified under Out-of-bounds Write. CVSS score: 8.8/10. Published 2019-12-18.
How severe is CVE-2019-8766?: High severity. CVSS v3 base score is 8.8 out of 10.