What is CVE-2026-86871?

CVE-2026-86871 is a medium-severity vulnerability in Apple macOS, classified under Improper Input Validation. CVSS score: 5.9/10. Published 2026-10-20.

How severe is CVE-2026-86871?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Integer overflow in Apple macOS

CVE-2026-86871

An integer underflow was addressed with improved input validation. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. An attacker with control of a network file server may be able to cause unexpected system termination.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2026-10-20 · last modified 2026-10-20.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Apple macOS

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-86871?: CVE-2026-86871 is a medium-severity vulnerability in Apple macOS, classified under Improper Input Validation. CVSS score: 5.9/10. Published 2026-10-20.
How severe is CVE-2026-86871?: Medium severity. CVSS v3 base score is 5.9 out of 10.