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CVE-2026-50418 is a security feature bypass vulnerability residing in the Windows operating system’s core access control mechanisms. The flaw stems from improper access control (CWE-284) within the Windows System, which permits an unauthorized attacker with local access to circumvent a security feature without requiring any user interaction or prior authentication. The vulnerability affects a range of current Windows releases, including Windows 11 versions 24H2, 25H2, and 26H1, as well as Windows Server 2022 and Windows Server 2025.
The root cause lies in the system’s failure to properly validate user credentials or authorization levels during security-sensitive operations. This allows malicious actors with limited or no privileges to escalate their access or bypass established security boundaries. The technical implementation of this access control failure can manifest through multiple vectors, including improper privilege escalation paths, insecure default configurations, or malformed security descriptors that fail to adequately restrict access to sensitive resources.
Attackers exploiting this vulnerability can potentially gain unauthorized access to system files, registry entries, network resources, or execute arbitrary code with elevated privileges. The flaw may be present in various Windows subsystems, including the authentication service, file system access controls, or network security components where proper authorization checks are either missing or inadequately implemented. The CVSS vector is CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N, indicating that exploitation must originate locally, but the attacker does not need existing privileges or user cooperation.
The attack complexity is rated low, suggesting no unusual race conditions or elaborate configurations are required once the attacker reaches the vulnerable interface. Successful exploitation can produce low confidentiality and integrity impacts, potentially exposing protected information and enabling limited unauthorized changes. Availability is unaffected, meaning the vulnerability is not expected to crash Windows or make the system unavailable. The scope remains unchanged, with any resulting impact staying within the same security authority. Microsoft has not publicly identified the particular Windows security feature that can be bypassed, making the installation of the July cumulative update the primary remedy. The vulnerability was published on July 14, 2026.
DailyCVE Form:
Platform: Windows System
Version: 11/Server 2022/2025
Vulnerability: Improper Access Control
Severity: MEDIUM (5.1)
date: 2026-07-14
Prediction: 2026-07-14 (Patched)
What Undercode Say:
Analytics:
- Attack Vector: Local (AV:L)
- Attack Complexity: Low (AC:L)
- Privileges Required: None (PR:N)
- User Interaction: None (UI:N)
- Scope: Unchanged (S:U)
- Confidentiality Impact: Low (C:L)
- Integrity Impact: Low (I:L)
- Availability Impact: None (A:N)
- EPSS: Not yet available
- VEX Confidence: High (0.9479)
Bash commands and codes related to the blog
Check Windows build version to determine if vulnerable
wmic os get buildnumber
For Windows 11 24H2 - vulnerable if build < 26100.8875
For Windows 11 25H2 - vulnerable if build < 26200.8875
For Windows 11 26H1 - vulnerable if build < 28000.2269
For Windows Server 2022 - vulnerable if build < 20348.5386
For Windows Server 2025 - vulnerable if build < 26100.33158
Check installed updates (KB numbers)
wmic qfe list brief /format:texttable
Verify specific KB installation (example for Windows 11 26H1)
wmic qfe where "HotFixID='KB5101649'" get HotFixID,InstalledOn
Alternative PowerShell check
Get-HotFix | Where-Object {$_.HotFixID -like "KB5101649"}
Check OS version details
systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"System Type"
Exploit:
Exploitation of CVE-2026-50418 requires local access to the target system. An attacker with physical access, a malicious peripheral, or an initial foothold via another vulnerability can trigger the flaw. The vulnerability can be exploited without any privileges or user interaction, as the CVSS vector indicates PR:N and UI:N. The low attack complexity means that no unusual race conditions, elaborate configurations, or hard-to-reproduce circumstances are required. Attackers can potentially gain unauthorized access to system files, registry entries, or execute arbitrary code with elevated privileges. The flaw may be exploited through improper privilege escalation paths, insecure default configurations, or malformed security descriptors.
Protection:
The primary and most effective protection is to install the July 2026 cumulative updates released by Microsoft on July 14, 2026. Specific fixed builds are:
– Windows 11 24H2: build 26100.8875 or later
– Windows 11 25H2: build 26200.8875 or later
– Windows 11 26H1: build 28000.2269 or later (KB5101649)
– Windows Server 2022: build 20348.5386 or later
– Windows Server 2025: build 26100.33158 or later
Additional mitigation strategies include:
- Implementing comprehensive patch management processes
- Configuring Windows security settings, disabling unnecessary services, and enforcing strong access controls
- Regularly auditing system permissions
- Implementing network segmentation and the principle of least privilege
- Configuring monitoring systems to detect unusual authentication patterns or privilege escalation attempts
Impact:
Successful exploitation allows an unauthorized attacker to bypass a Windows security feature locally. The attacker may obtain some protected information and make limited unauthorized changes. The vulnerability poses significant risks to enterprise environments as it enables local attackers to bypass security features designed to protect against unauthorized access. The impact extends beyond simple privilege escalation to potentially enable lateral movement within networks, data exfiltration, system compromise, and persistent access. Organizations may experience unauthorized access to sensitive information, system integrity violations, and potential compliance breaches. While availability is not affected, the low confidentiality and integrity impacts can still lead to serious security incidents, especially in environments where local access is not strictly controlled.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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