Microsoft Windows Link Following
CVE-2026-81963 is a high-severity improper link resolution before file access vulnerability in Windows 11 version 23H2 from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 10.0.22631.7582 as the first without the flaw, so updating Windows 11 version 23H2 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on September 8, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Windows 11 version 23H2 to 10.0.22631.7582 or a later version.
- Update Windows 11 Version 24H2 to 10.0.26100.9445 or a later version.
- Update Windows 11 Version 25H2 to 10.0.26200.9445 or a later version.
- CISA's 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.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 up to, but not including, 10.0.22631.7582 | 10.0.22631.7582 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 up to, but not including, 10.0.26100.9445 | 10.0.26100.9445 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 up to, but not including, 10.0.26200.9445 | 10.0.26200.9445 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 up to, but not including, 10.0.28000.2954 | 10.0.28000.2954 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 up to, but not including, 10.0.26100.33438 | 10.0.26100.33438 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 up to, but not including, 10.0.26100.33438 | 10.0.26100.33438 |
| Microsoft | Windows 11 23h2 | before 10.0.22631.7582 | 10.0.22631.7582 |
| Microsoft | Windows 11 24h2 | before 10.0.26100.9445 | 10.0.26100.9445 |
| Microsoft | Windows 11 25h2 | before 10.0.26200.9445 | 10.0.26200.9445 |
| Microsoft | Windows 11 26h1 | before 10.0.28000.2954 | 10.0.28000.2954 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).
Official description
Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Link Resolution Before File Access
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
How developers prevent this class of flaw
- Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
More Improper Link Resolution Before File Access vulnerabilities (CWE-59)
Timeline
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Record last changed materially (score, affected products, status or references).
- Deadline for US federal agencies to remediate, set by CISA.
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-81963US Government Resource
Our coverage
Recent Improper Link Resolution Before File Access vulnerabilities
- 7.0 High severity
- 7.8 High severity
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- 7.1 High severity
- 7.8 High severity
- 8.5 High severity
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