CVE-2026-81963
KEV: known exploited SSVC: activeWindows Update Stack Elevation of Privilege Vulnerability
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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
Attack conditions and impact
Derived from the CNA (via NVD) CVSS 3.1 vector| Metric | Value | Meaning |
|---|---|---|
| Attack vector AV | L | Local |
| Attack complexity AC | L | Low (easy) |
| Privileges required PR | L | Regular user |
| User interaction UI | N | None |
| Scope S | U | Unchanged |
| Confidentiality C | H | High |
| Integrity I | H | High |
| Availability A | H | High |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Description
Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.
CISA KEV entry
Microsoft Windows Link Following Vulnerability — Microsoft / Windows
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.
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
CVSS assessments
| Provider | Version | Score | Vector |
|---|---|---|---|
| NVD / [email protected] (Secondary) | 3.1 | 7.8 HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| CNA / microsoft | 3.1 | 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 |
Affected products and packages
CNA (CVE.org)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | affected: 10.0.22631.0 … < 10.0.22631.7582 |
| Microsoft | Windows 11 Version 23H2 | affected: 10.0.22631.0 … < 10.0.22631.7582 |
| Microsoft | Windows 11 Version 24H2 | affected: 10.0.26100.0 … < 10.0.26100.9445 |
| Microsoft | Windows 11 Version 25H2 | affected: 10.0.26200.0 … < 10.0.26200.9445 |
| Microsoft | Windows 11 version 26H1 | affected: 10.0.28000.0 … < 10.0.28000.2954 |
| Microsoft | Windows Server 2025 | affected: 10.0.26100.0 … < 10.0.26100.33438 |
| Microsoft | Windows Server 2025 (Server Core installation) | affected: 10.0.26100.0 … < 10.0.26100.33438 |
NVD CPE (9)
Show CPE list
| Vendor | Product | Range | CPE |
|---|---|---|---|
| microsoft | windows_11_23h2 | < 10.0.22631.7582 | cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:* |
| microsoft | windows_11_23h2 | < 10.0.22631.7582 | cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:* |
| microsoft | windows_11_24h2 | < 10.0.26100.9445 | cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:* |
| microsoft | windows_11_24h2 | < 10.0.26100.9445 | cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:* |
| microsoft | windows_11_25h2 | < 10.0.26200.9445 | cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:* |
| microsoft | windows_11_25h2 | < 10.0.26200.9445 | cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:* |
| microsoft | windows_11_26h1 | < 10.0.28000.2954 | cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:arm64:* |
| microsoft | windows_11_26h1 | < 10.0.28000.2954 | cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:x64:* |
| microsoft | windows_server_2025 | < 10.0.26100.33438 | cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:* |
Linux distribution status
References (2)
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963 NVD, CNA PatchVendor Advisoryvendor-advisorypatch
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81963 NVD, ADP CISA-ADP US Government Resourcegovernment-resource