What is CVE-2026-39873?

CVE-2026-39873 is a critical-severity vulnerability in Apple Macos, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2026-07-27.

How severe is CVE-2026-39873?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Apple Macos

CVE-2026-39873

The issue was addressed with improved memory handling. This issue is fixed in macOS Sequoia 15.7.8, macOS Sonoma 14.8.8, macOS Tahoe 26.6. Connecting to a malicious SMB server may lead to unexpected system termination.

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Apple Macos — versions 0

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

References

product-security@apple.com (Release Notes, Vendor Advisory)
product-security@apple.com (Release Notes, Vendor Advisory)
product-security@apple.com (Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2026-39873?: CVE-2026-39873 is a critical-severity vulnerability in Apple Macos, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2026-07-27.
How severe is CVE-2026-39873?: Critical severity. CVSS v3 base score is 9.8 out of 10.