CVE-2026-21255
HIGHCVSS 8.8/10EPSS 0.36%
Last modified
CVE-2026-21255 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.. EPSS estimates a 0.36% chance of exploitation in the next 30 days.
Description
Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 1607 | < 10.0.14393.8868 |
| Microsoft | Windows 10 1809 | < 10.0.17763.8389 |
| Microsoft | Windows 10 21h2 | < 10.0.19044.6937 |
| Microsoft | Windows 10 22h2 | < 10.0.19045.6937 |
| Microsoft | Windows 11 23h2 | < 10.0.22631.6649 |
| Microsoft | Windows 11 24h2 | < 10.0.26100.7781 |
| Microsoft | Windows 11 25h2 | < 10.0.26200.7781 |
| Microsoft | Windows Server 2016 | < 10.0.14393.8868 |
| Microsoft | Windows Server 2019 | < 10.0.17763.8389 |
| Microsoft | Windows Server 2022 | < 10.0.20348.4711 |
| Microsoft | Windows Server 2022 23h2 | < 10.0.25398.2149 |
| Microsoft | Windows Server 2025 | < 10.0.26100.32313 |
References
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-21255?
Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
How severe is CVE-2026-21255?
CVE-2026-21255 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.36% probability of exploitation in the next 30 days.
How do I fix CVE-2026-21255?
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
- Uncovering a hidden BOLA in Appsmith's snapshot logicStrix autonomously discovered a BOLA/IDOR vulnerability in Appsmith's snapshot deletion path.
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Are you affected by CVE-2026-21255?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST