CVE-2026-100217 in Windows
Summary
by MITRE • 10/13/2026
Improper privilege management in Windows Group Policy allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves improper privilege management within the Microsoft Windows Group Policy infrastructure, a critical component of enterprise identity and access control systems. This flaw specifically enables an authenticated local user or process with sufficient permissions to manipulate group policy objects in a manner that circumvents intended security boundaries. The core technical issue lies in how the system validates and applies configuration changes related to privilege assignments during the processing of Group Policy settings. When these validation checks are insufficient, it creates a pathway for attackers to modify policies governing local account privileges without triggering appropriate administrative alerts or requiring higher-level credentials than originally anticipated by the system design.
From a technical perspective, this flaw typically manifests through mechanisms that allow users with write access to specific policy containers or registry keys associated with Group Policy preferences to alter security descriptors or privilege assignments. By exploiting these misconfigurations, an attacker can escalate their privileges from standard user rights to those of higher-privileged accounts, such as administrators or system-level services. This process often involves modifying the Local Security Authority (LSA) settings or manipulating token manipulation features that are exposed through Group Policy templates. The exploitation does not require remote code execution or network-based attacks but relies on local access and existing write permissions within specific policy scopes, making it particularly dangerous in environments where users have broad control over their own machine configurations or shared administrative workstations.
The operational impact of this vulnerability is severe, as successful exploitation leads to full system compromise at the local level. Once an attacker achieves elevated privileges, they can bypass security controls such as User Account Control (UAC), access sensitive data stored locally, install persistent malware with high-level permissions, and potentially pivot to other systems within the network if lateral movement tools are available. This undermines the principle of least privilege, which is foundational to secure system architecture. In enterprise environments where Group Policy is used extensively for centralized management, this flaw can be leveraged by insider threats or attackers who have gained initial foothold through phishing or physical access, allowing them to establish a persistent and powerful presence on critical endpoints.
This vulnerability aligns with CWE-269, which classifies Improper Privilege Management, indicating that the software does not properly assign privileges based on user roles or actions. Furthermore, it maps to MITRE ATT&CK techniques related to privilege escalation, specifically those involving local system configuration changes and abuse of trusted processes like Group Policy processing mechanisms such as gpupdate.exe or associated DLLs. The attack vector is classified as Local (L), requiring the attacker to have some form of authenticated access to the target machine prior to exploitation.
Mitigation strategies must focus on both technical controls and administrative policies. Organizations should restrict write permissions to critical Group Policy folders and registry keys, ensuring that only designated administrators can modify security-related settings. Regular auditing of group policy objects is essential to detect unauthorized changes promptly. Additionally, applying vendor-provided patches that address the specific validation logic flaws in the Group Policy engine is paramount. Security teams should also implement strict endpoint detection and response (EDR) policies to monitor for anomalous privilege escalation attempts via system configuration tools. Enabling enhanced logging for security policy modifications allows for faster incident response when such activities are detected, thereby reducing the window of opportunity for attackers to exploit this weakness effectively.