CVE-2026-81963

Published Sep 8, 2026

Last updated 2 months ago

Exploit known CVSS high 7.8

Zero-day

System

Server

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-81963 is an elevation-of-privilege vulnerability found within the Windows Update Stack, the component responsible for managing and installing Windows updates. The flaw arises from two primary weaknesses: improper link resolution before file access, often referred to as "link following," and inadequate access control. A locally authenticated attacker with low privileges can exploit these weaknesses to elevate their privileges to SYSTEM level. This exploitation can occur without requiring any user interaction. Microsoft addressed this vulnerability as part of its September 2026 Patch Tuesday release, affecting various versions of Windows 11 and Windows Server 2025.

Description: Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.
Source: secure@microsoft.com
NVD status: Analyzed
Products: windows_11_23h2, windows_11_24h2, windows_11_25h2, windows_11_26h1, windows_server_2025

Risk scores

CVSS 3.1

Type: Secondary
Base score: 7.8
Impact score: 5.9
Exploitability score: 1.8
Vector string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: Microsoft Windows Link Following Vulnerability
Exploit added on: Sep 8, 2026
Exploit action due: Sep 22, 2026
Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Weaknesses

secure@microsoft.com: CWE-59

Hype score: Not currently trending

Configurations

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            "versionEndExcluding": "10.0.22631.7582",
            "vulnerable": true
          },
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            "versionEndExcluding": "10.0.22631.7582",
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          },
          {
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            "versionEndExcluding": "10.0.26100.9445",
            "vulnerable": true
          },
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            "vulnerable": true
          },
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            "versionEndExcluding": "10.0.26200.9445",
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          },
          {
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          },
          {
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            "versionEndExcluding": "10.0.28000.2954",
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          },
          {
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        "negate": false,
        "operator": "OR"
      }
    ]
  }
]

References

Sources include official advisories and independent security research.