CVE-2021-26866
HIGHCVSS 7.1/10EPSS 1.11%
Last modified
CVE-2021-26866 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. Windows Update Service Elevation of Privilege Vulnerability. EPSS estimates a 1.11% chance of exploitation in the next 30 days.
Description
Windows Update Service Elevation of Privilege Vulnerability
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 | All versions |
| Microsoft | Windows 10 | 20h2 |
| Microsoft | Windows 10 | 1607 |
| Microsoft | Windows 10 | 1803 |
| Microsoft | Windows 10 | 1809 |
| Microsoft | Windows 10 | 1909 |
| Microsoft | Windows 10 | 2004 |
| Microsoft | Windows Server 2016 | All versions |
| Microsoft | Windows Server 2016 | 20h2 |
| Microsoft | Windows Server 2016 | 1909 |
| Microsoft | Windows Server 2016 | 2004 |
| Microsoft | Windows Server 2019 | All versions |
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26866Patch, Vendor Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-286/Third Party Advisory, VDB Entry
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26866Patch, Vendor Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-286/Third Party Advisory, VDB Entry
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-26866?
Windows Update Service Elevation of Privilege Vulnerability
How severe is CVE-2021-26866?
CVE-2021-26866 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 1.11% probability of exploitation in the next 30 days.
How do I fix CVE-2021-26866?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-26866?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST