Threat Intelligence / CVE / CVE-2026-81963

CVE-2026-81963 — Microsoft Windows 11 version 23H2

CISA KEV

CVSS v3.1 7.8 (HIGH) · Priority 9/10 · Published 2026-09-08

As of 2026-09-08, CVE-2026-81963 is a HIGH-severity vulnerability in Microsoft Windows 11 version 23H2, CVSS v3.1 7.8. It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-09-08), with a US federal remediation deadline of 2026-09-22. Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2026-81963, most recently “September 2026 Microsoft Patch Tuesday — Record 966+ Vulnerabilities with Two Actively Exploited Zero-Days (CVE-2026-81963, CVE-2026-85880) and Multiple Critical Wormable RCEs”.

Last updated: 2026-09-08

What is CVE-2026-81963?

Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.

The record classifies CVE-2026-81963 under weakness classes CWE-59, CWE-284. Its CVSS v3 base vector states that the flaw requires local access to the host, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality, integrity, availability. 7 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 5 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 7.8 — HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
CISA KEV: Listed since 2026-09-08, federal remediation deadline 2026-09-22
Threadlinqs priority: 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published: 2026-09-08

Is CVE-2026-81963 being exploited?

CISA added CVE-2026-81963 to the Known Exploited Vulnerabilities catalog on 2026-09-08, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-09-22 under BOD 22-01. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

Microsoft: Windows 11 version 23H2, Windows 11 Version 23H2, Windows 11 Version 24H2, Windows 11 Version 25H2, Windows 11 version 26H1, Windows Server 2025, Windows Server 2025 (Server Core installation)

How to fix CVE-2026-81963

The record marks a vendor fix as available for CVE-2026-81963. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963. Because CVE-2026-81963 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-09-22. 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-2026-81963

2 tracked threats in the Threadlinqs corpus reference CVE-2026-81963, either in the campaign’s CVE list or as an indicator on the campaign record.

September 2026 Microsoft Patch Tuesday — Record 966+ Vulnerabilities with Two Actively Exploited Zero-Days (CVE-2026-81963, CVE-2026-85880) and Multiple Critical Wormable RCEs — CRITICAL · 2026-09-08
Microsoft September 2026 Patch Tuesday — 999 CVEs, 3 actively exploited zero-days (CVE-2026-85880, CVE-2026-81963, CVE-2026-85046) — CRITICAL · 2026-09-08

Sources

Enriched from CVE.org, NVD, CISA KEV, GitHub Security Advisories. Last verified by Threadlinqs on 2026-09-08. This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch

msrc.microsoft.com — vendor advisory

Full detection coverage & IOCs for threats exploiting CVE-2026-81963 are available via the Threadlinqs MCP server (Purple tier). View plans →

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