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VulnerabilityCVE-2026-85921Published 2026-09-14

CVE-2026-85921 — Microsoft Windows 11 version 26H1

high

As of 2026-09-18, CVE-2026-85921 is a HIGH-severity vulnerability in Microsoft Windows 11 version 26H1, CVSS v3.1 8.2, EPSS 0.2% (18.0th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-85921, most recently “Microsoft September 2026 Cloud Disclosure: 18 Elevation-of-Privilege, Information-Disclosure, and Spoofing Flaws Across Azure and Copilot AI Products, Plus a Windows Secure Kernel EoP (CVE-2026-85921)”.

CVSS v3.1
8.2/10High
EPSS
0.2%Higher than 18.0% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
1Campaigns referencing it
Priority
4.8/10Threadlinqs triage score
Published
Updated 2026-09-17
CVSS v3.1 8.2 (HIGH) · EPSS 0.2% (higher than 18.0% of all scored CVEs) · Priority 4.8/10 · Published 2026-09-14

Last updated:

What is CVE-2026-85921?

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

The record classifies CVE-2026-85921 under weakness class CWE-415. Its CVSS v3 base vector states that the flaw requires local access to the host, needs high-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 55 days ago.

Severity and exploitation probability

CVSS v3.1 base score
8.2 — HIGH
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
EPSS (FIRST)
0.2% probability of exploitation in the next 30 days, higher than 18.0% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
4.8/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-09-14, last modified 2026-09-17

Is CVE-2026-85921 being exploited?

No public exploitation evidence for CVE-2026-85921 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-09-17. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

Affected products and versions

How to fix CVE-2026-85921

Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85921. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2026-85921

1 tracked threat in the Threadlinqs corpus references CVE-2026-85921, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch