Windows
CVE-2026-21255
HIGH
Severity by source
AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
AnalysisAI
Windows Hyper-V fails to properly enforce access controls, enabling local authenticated users to circumvent security features and gain unauthorized system access. This high-severity flaw affects Windows 10, Windows 11, Windows Server 2022, and Hyper-V implementations, allowing privileged attackers to escalate privileges across system boundaries. No patch is currently available for this vulnerability.
Technical ContextAI
Classified as CWE-284 (Improper Access Control). Affects Windows 10 1607. Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
RemediationAI
Monitor vendor advisories for a patch.
Windows MSHTML component contains a remote code execution vulnerability that allows attackers to craft malicious ActiveX
Windows Win32k contains an out-of-bounds write vulnerability enabling local privilege escalation to SYSTEM, exploited by
The Windows VBScript engine contains a remote code execution vulnerability in object handling that allows full system co
Windows Win32k fails to properly handle objects in memory, allowing local privilege escalation exploited in the wild in
A privilege escalation vulnerability (CVSS 5.5). Risk factors: actively exploited (KEV-listed), EPSS 94% exploitation pr
Windows Kernel contains a TOCTOU race condition vulnerability allowing local privilege escalation, exploited by the OilR
Windows Internet Shortcut Files (.url) contain an external control vulnerability (CVE-2025-33053, CVSS 8.8) that enables
Windows SMB contains an improper access control vulnerability (CVE-2025-33073, CVSS 8.8) enabling authenticated attacker
Twonky Server 8.5.2 on Linux and Windows allows unauthenticated access to the admin log file through a web service API b
An unrestricted file upload vulnerability exists in MiniWeb HTTP Server <= Build 300 that allows unauthenticated remote
FreeFloat FTP Server contains multiple critical design flaws that allow unauthenticated remote attackers to upload arbit
Serviio Media Server versions 1.4 through 1.8 on Windows contain an unauthenticated command injection in the /rest/actio
Same weakness CWE-284 – Improper Access Control
View allShare
External POC / Exploit Code
Leaving vuln.today