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Actively exploitedCVSS 7.8 · HIGH

CVE-2026-81963Privilege escalation in Windows Update Stack

Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.

View on NVD

Analysis

Una vulnerabilidad en el componente Windows Update Stack permite que un atacante con acceso local eleve sus privilegios hasta el nivel de SYSTEM mediante el seguimiento de enlaces simbólicos. Este fallo está siendo explotado activamente para comprometer estaciones de trabajo y servidores Windows modernos. Se recomienda actualizar de inmediato para mitigar el riesgo de compromiso total del sistema.

Relevant roles

Windowsciberseguridad

Severity

Score: 7.8(HIGH)
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
AV: LOCAL
AC: LOW
PR: LOW
UI: NONE
S: UNCHANGED
C: HIGH
I: HIGH
A: HIGH
Weakness (CWE): CWE-59CWE-284

CISA KEV

Added to KEV: 2026-09-08
Federal patch deadline: 2026-09-22
Known ransomware use: Unknown
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.

EPSS

No EPSS score yet (CVE may be too fresh).

Affects

microsoft:windows_11_23h2microsoft:windows_11_24h2microsoft:windows_11_25h2microsoft:windows_11_26h1microsoft:windows_server_2025

Technical description

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

Published: 9/8/2026, 6:21:00 PM
Last modified: 9/8/2026, 7:28:31 PM

References

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