CVEs / CVE-2026-81963
CVE-2026-81963: Microsoft Windows Link Following Vulnerability
- Known exploited in the CISA KEV catalog since 8 Sep 2026
- high 7.8 CVSS 3.1 (from the CNA)
- EPSS 0.39% chance of exploitation in the next 30 days, higher than 33% of CVEs (30 Oct 2026)
- Last changed at its sources
Are you affected? Check your servers with Stackurity: it lists the software on each server and the vulnerabilities to fix first.
Check your servers with Stackurity Already using Stackurity? Search for CVE-2026-81963
Summary
Microsoft Windows Update Stack contains a link following vulnerability that allows a local attacker to escalate privileges locally up to SYSTEM.
Description
Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Windows 11 version 23H2 | from 10.0.22631.0, before 10.0.22631.7582 | 10.0.22631.7582 |
| Microsoft Windows 11 Version 23H2 | from 10.0.22631.0, before 10.0.22631.7582 | 10.0.22631.7582 |
| Microsoft Windows 11 Version 24H2 | from 10.0.26100.0, before 10.0.26100.9445 | 10.0.26100.9445 |
| Microsoft Windows 11 Version 25H2 | from 10.0.26200.0, before 10.0.26200.9445 | 10.0.26200.9445 |
| Microsoft Windows 11 version 26H1 | from 10.0.28000.0, before 10.0.28000.2954 | 10.0.28000.2954 |
| Microsoft Windows Server 2025 | from 10.0.26100.0, before 10.0.26100.33438 | 10.0.26100.33438 |
| Microsoft Windows Server 2025 (Server Core installation) | from 10.0.26100.0, before 10.0.26100.33438 | 10.0.26100.33438 |
Exploitation
| In CISA KEV since | 8 Sep 2026 |
|---|---|
| Due date for US federal agencies | 22 Sep 2026 |
| Used in ransomware campaigns | 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. |
Severity
| CVSS 3.1 | 7.8 highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-59, CWE-284 |
References
- CVE-2026-81963 on NVD
- CVE-2026-81963 in the CISA KEV catalog
- https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-81963 (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (cited by CISA)
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (cited by CISA)
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81963 Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81963 US Government Resource
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
This product uses data from the NVD API but is not endorsed or certified by the NVD.