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CVE-2026-81963

Windows Update Stack Elevation of Privilege Vulnerability

HIGH
7.8
CVSS Score
Published: September 8, 2026 at 05:19 PM UTC
Updated: October 14, 2026 at 11:14 PM UTC
5 products affected across 1 vendorWindows Server 2025Windows 11 24H2Windows 11 23H2

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Severity
HIGH7.8
Exploitation
CISA KEV
Exploit prediction
EPSS 0.4%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score0.4%

EPSS (Exploit Prediction Scoring System) estimates a 0.4% chance this CVE is exploited in the wild within the next 30 days — higher than 33% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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

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.
Ransomware Use
Unknown
Added to KEV
Sep 8, 2026
Remediation Due
Sep 22, 2026
37 days overdue
Notes
https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-81963
BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
https://nvd.nist.gov/vuln/detail/CVE-2026-81963

Description

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Windows 11 23H2· Microsoft
95%
v < 10.0.22631.758210.0.22631.0 ≤ v < 10.0.22631.758210.0.22631.0
Affected range stops below 10.0.22631.7582, so it looks safe — our inference, not a vendor statement
Windows 11 24H2· Microsoft
95%
v < 10.0.26100.944510.0.26100.0 ≤ v < 10.0.26100.944510.0.26100.0
Affected range stops below 10.0.26100.9445, so it looks safe — our inference, not a vendor statement
Windows 11 25H2· Microsoft
95%
v < 10.0.26200.944510.0.26200.0 ≤ v < 10.0.26200.944510.0.26200.0
Affected range stops below 10.0.26200.9445, so it looks safe — our inference, not a vendor statement
Windows 11 26H1· Microsoft
95%
v < 10.0.28000.295410.0.28000.0 ≤ v < 10.0.28000.295410.0.28000.0
Affected range stops below 10.0.28000.2954, so it looks safe — our inference, not a vendor statement
Windows Server 2025· Microsoft
95%
v < 10.0.26100.3343810.0.26100.0 ≤ v < 10.0.26100.3343810.0.26100.0
Affected range stops below 10.0.26100.33438, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Vendor AdvisoryPatch
Source: cverecord
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81963

SSVC — Action Prioritization

SSVCActiveNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGH[email protected]
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-59CWE-284

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