---
title: "CVE-2026-81963: Microsoft Windows Link Following Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-81963/
description: "CVE-2026-81963 (Microsoft Windows): Exploited in the wild (CISA KEV). Improper link resolution before file access ('link following') in Windows Update Stack…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-08
date_modified: 2026-10-14
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-81963"
kev: true
cvss: 7.8
epss: 0.00393
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-81963: Microsoft Windows Link Following Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Microsoft Windows. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-09-08, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-09-22 ; treat that as the outer limit, not the target.
- EPSS 0.4% , percentile 32: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 32% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
- Editorial verdict: Patch this week. Windows Zero-Days: Update Stack and ALPC EoP (Sep 2026) — Make sure every Windows machine has the September 2026 or a later cumulative update; both bugs are exploited, but an attacker needs code running on the box first.

## What it is

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

## Affected products (CVE record)

- Microsoft Windows 11 version 23H2: 10.0.22631.0 < 10.0.22631.7582
- Microsoft Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.7582
- Microsoft Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.9445
- Microsoft Windows 11 Version 25H2: 10.0.26200.0 < 10.0.26200.9445
- Microsoft Windows 11 version 26H1: 10.0.28000.0 < 10.0.28000.2954
- Microsoft Windows Server 2025: 10.0.26100.0 < 10.0.26100.33438
- Microsoft Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.33438

## Severity

- microsoft CVSS 3.1: 7.8 `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`

## Exploitation

- CISA KEV: added 2026-09-08; federal due date 2026-09-22. Known ransomware use: Unknown.
- CISA 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.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.39% probability of exploitation activity in the next 30 days; percentile 32.

## Sources

- [Windows Update Stack Elevation of Privilege Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963)
- [Listed in CISA KEV notes (msrc.microsoft.com)](https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-81963)
- [CVE.org record CVE-2026-81963](https://www.cve.org/CVERecord?id=CVE-2026-81963)
- [NVD entry CVE-2026-81963](https://nvd.nist.gov/vuln/detail/CVE-2026-81963)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81963)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)

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Source page: https://erroneo.us/security/cve/CVE-2026-81963/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt