# CVE-2026-81963 — Microsoft Windows 11 version 23H2 **CISA KEV** > 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](https://cwe.mitre.org/data/definitions/59.html), [CWE-284](https://cwe.mitre.org/data/definitions/284.html). 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](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963). Vendor advisory: [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963](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](https://intel.threadlinqs.com/threat/TL-2026-2398) — 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)](https://intel.threadlinqs.com/threat/TL-2026-2407) — 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](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963) Canonical: https://intel.threadlinqs.com/cve/CVE-2026-81963 Full detection coverage and IOCs for threats exploiting CVE-2026-81963 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp