What is CVE-2026-86889?

CVE-2026-86889 is a medium-severity vulnerability in Apple macOS, classified under Improper Certificate Validation. CVSS score: 4.8/10. Published 2026-09-14.

How severe is CVE-2026-86889?

Medium severity. CVSS v3 base score is 4.8 out of 10.

Vulnerability in Apple macOS

CVE-2026-86889

A certificate validation issue was addressed with improved certificate validation. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. An attacker in a privileged network position may be able to intercept network traffic.

Vulnerability class: Improper Certificate Validation

Published 2026-09-14 · last modified 2026-09-16.

CVSS v3 metric

CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (9.4th percentile), scored 2026-10-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 9.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Apple macOS

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

support.apple.com/en-us/149035 (Vendor Advisory)
support.apple.com/en-us/149042 (Vendor Advisory)
support.apple.com/en-us/149043 (Vendor Advisory)

Frequently asked questions

What is CVE-2026-86889?: CVE-2026-86889 is a medium-severity vulnerability in Apple macOS, classified under Improper Certificate Validation. CVSS score: 4.8/10. Published 2026-09-14.
How severe is CVE-2026-86889?: Medium severity. CVSS v3 base score is 4.8 out of 10.