What is CVE-2026-85921?

CVE-2026-85921 is a high-severity vulnerability in Microsoft Windows 11 26h1, classified under Double Free. CVSS score: 8.2/10. Published 2026-09-14.

How severe is CVE-2026-85921?

High severity. CVSS v3 base score is 8.2 out of 10.

Double Free in Microsoft Windows 11 26h1

CVE-2026-85921

Double free in Windows Secure Kernel Mode allows an authorized attacker to elevate privileges locally.

Vulnerability class: Double Free

Published 2026-09-14 · last modified 2026-09-29.

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (28.4th percentile), scored 2026-10-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-415 — Double Free

References

Windows Secure Kernel Mode Elevation of Privilege Vulnerability (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-85921?: CVE-2026-85921 is a high-severity vulnerability in Microsoft Windows 11 26h1, classified under Double Free. CVSS score: 8.2/10. Published 2026-09-14.
How severe is CVE-2026-85921?: High severity. CVSS v3 base score is 8.2 out of 10.