📄 Description (English)
Time-of-check time-of-use (toctou) race condition in Windows Installer allows an authorized attacker to elevate privileges locally.
🤖 AI Executive Summary
CVE-2026-20816 is a time-of-check time-of-use (TOCTOU) race condition in Windows Installer affecting multiple Windows 10 and Windows 11 versions, as well as Windows Server 2008 SP2. An authorized local attacker can exploit this vulnerability to elevate privileges to SYSTEM level. With a CVSS score of 7.8 and no public exploit currently available, this represents a significant but manageable risk requiring prompt patching across enterprise environments.
📄 Description (Arabic)
🤖 AI Intelligence Analysis Analyzed: Apr 28, 2026 12:02
🇸🇦 Saudi Arabia Impact Assessment
This vulnerability poses significant risk to Saudi government agencies (NCA, CITC), banking sector (SAMA-regulated institutions, major banks), healthcare organizations (MOH facilities), energy sector (ARAMCO, utilities), and telecommunications providers (STC, Mobily). The privilege escalation capability is particularly concerning for critical infrastructure operators and financial institutions where Windows systems manage sensitive operations. Organizations with legacy Windows Server 2008 SP2 deployments face elevated risk due to extended support ending and slower patching cycles.
🏢 Affected Saudi Sectors
Banking and Financial Services
Government and Public Administration
Healthcare
Energy and Utilities
Telecommunications
Critical Infrastructure
Defense and Security
🎯 MITRE ATT&CK Techniques
⚖️ Saudi Risk Score (AI)
7.2
/ 10.0
🔧 Remediation Steps (English)
IMMEDIATE ACTIONS:
1. Inventory all Windows 10 (versions 1607, 1809, 21H2, 22H2) and Windows 11 (23H2, 24H2, 25H2) systems, plus Windows Server 2008 SP2 installations
2. Prioritize patching for systems with local user access and elevated privilege requirements
3. Implement application whitelisting to restrict Windows Installer execution
PATCHING GUIDANCE:
1. Apply Microsoft security updates immediately upon release for affected OS versions
2. For Windows Server 2008 SP2: Consider migration planning as extended support ended in January 2020
3. Test patches in non-production environments before enterprise deployment
COMPENSATING CONTROLS (if patching delayed):
1. Restrict local administrator account usage and implement privileged access management (PAM)
2. Disable Windows Installer for standard users via Group Policy (Set-GPRegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows\Installer' -Name 'DisableMSI' -Value 2)
3. Monitor Windows Installer activity: Enable auditing for process creation and file system access
4. Implement application control policies to prevent unauthorized installer execution
DETECTION RULES:
1. Monitor Event ID 11 (FileCreate) for suspicious .msi file creation in temp directories
2. Alert on Windows Installer (msiexec.exe) spawning with SYSTEM privileges
3. Track rapid file creation/deletion patterns in %TEMP% and %APPDATA% directories
4. Monitor for privilege escalation attempts following msiexec.exe execution
🔧 خطوات المعالجة (العربية)
الإجراءات الفورية:
1. حصر جميع أنظمة Windows 10 (الإصدارات 1607، 1809، 21H2، 22H2) و Windows 11 (23H2، 24H2، 25H2)، بالإضافة إلى تثبيتات Windows Server 2008 SP2
2. إعطاء الأولوية لتصحيح الأنظمة التي تتمتع بإمكانية الوصول المحلي ومتطلبات الامتيازات المرتفعة
3. تطبيق قائمة التطبيقات المسموحة لتقييد تنفيذ برنامج تثبيت Windows
إرشادات التصحيح:
1. تطبيق تحديثات أمان Microsoft فوراً عند إصدارها للإصدارات المتأثرة
2. بالنسبة لـ Windows Server 2008 SP2: النظر في تخطيط الهجرة حيث انتهت الدعاية الممتدة في يناير 2020
3. اختبار التصحيحات في بيئات غير الإنتاج قبل النشر على مستوى المؤسسة
الضوابط البديلة (إذا تأخر التصحيح):
1. تقييد استخدام حساب المسؤول المحلي وتطبيق إدارة الوصول المميز
2. تعطيل برنامج تثبيت Windows للمستخدمين العاديين عبر Group Policy
3. مراقبة نشاط برنامج تثبيت Windows: تفعيل التدقيق لإنشاء العمليات والوصول إلى نظام الملفات
4. تطبيق سياسات التحكم في التطبيقات لمنع تنفيذ المثبت غير المصرح به
قواعد الكشف:
1. مراقبة Event ID 11 لإنشاء ملفات .msi مريبة في مجلدات مؤقتة
2. التنبيه على برنامج تثبيت Windows (msiexec.exe) الذي يعمل بامتيازات SYSTEM
3. تتبع أنماط إنشاء/حذف الملفات السريعة في مجلدات %TEMP% و %APPDATA%
4. مراقبة محاولات الارتقاء بالامتيازات بعد تنفيذ msiexec.exe
📋 Regulatory Compliance Mapping
🟢 NCA ECC 2024
ECC 2024 A.5.1.1 - Access Control Policies
ECC 2024 A.5.2.1 - User Registration and De-registration
ECC 2024 A.5.3.1 - Access Rights Review
ECC 2024 A.8.1.1 - Asset Inventory and Control
ECC 2024 A.12.2.1 - Change Management
🔵 SAMA CSF
SAMA CSF ID.AM-1 - Asset Management
SAMA CSF PR.AC-1 - Access Control
SAMA CSF PR.AC-4 - Access Rights Management
SAMA CSF DE.CM-1 - Detection and Analysis
SAMA CSF RC.RP-1 - Recovery Planning
🟡 ISO 27001:2022
ISO 27001:2022 A.5.3 - Segregation of Duties
ISO 27001:2022 A.8.1 - User Endpoint Devices
ISO 27001:2022 A.8.2 - Privileged Access Rights
ISO 27001:2022 A.8.3 - Information Access Restriction
ISO 27001:2022 A.12.6 - Change Management
🟣 PCI DSS v4.0.1
PCI DSS 2.1 - Configuration Standards
PCI DSS 6.2 - Security Patches
PCI DSS 7.1 - Limit Access by Business Need
PCI DSS 10.2 - User Access Logging
📦 Affected Products / CPE 19 entries
microsoft:windows_10_1607
microsoft:windows_10_1607
microsoft:windows_10_1809
microsoft:windows_10_1809
microsoft:windows_10_21h2
microsoft:windows_10_22h2
microsoft:windows_11_23h2
microsoft:windows_11_24h2
microsoft:windows_11_25h2
microsoft:windows_server_2008:-
microsoft:windows_server_2008:-
microsoft:windows_server_2008:r2
microsoft:windows_server_2012:-
microsoft:windows_server_2012:r2
microsoft:windows_server_2016
microsoft:windows_server_2019
microsoft:windows_server_2022
microsoft:windows_server_2022_23h2
microsoft:windows_server_2025