📄 Description (English)
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. This may be used to crash the server, or for privilege escalation if the X server runs as root.
🤖 AI Executive Summary
A stack-based buffer overflow vulnerability in X.Org X server and Xwayland allows unauthenticated attackers to crash the display server or achieve privilege escalation if running as root. The flaw exists in the _XkbSetMapChecks() function where a fixed 256-element buffer is indexed by client-controlled keyboard type values without proper bounds checking. This vulnerability poses significant risk to Saudi organizations relying on X11/Xwayland for remote desktop and virtualization infrastructure.
📄 Description (Arabic)
🤖 AI Intelligence Analysis Analyzed: Jun 9, 2026 01:37
🇸🇦 Saudi Arabia Impact Assessment
High impact on Saudi government entities (NCA, NCSC infrastructure), financial institutions using X11-based trading terminals and remote access solutions, healthcare facilities with PACS systems, and telecommunications providers (STC, Mobily) operating Linux-based infrastructure. Energy sector (ARAMCO, SEC) systems utilizing X server for SCADA visualization face privilege escalation risks. Educational institutions and research centers with shared computing resources are vulnerable to denial of service attacks.
🏢 Affected Saudi Sectors
Banking and Financial Services
Government and Public Administration
Healthcare and Medical Institutions
Energy and Utilities
Telecommunications
Education and Research
Defense and Security
🎯 MITRE ATT&CK Techniques
⚖️ Saudi Risk Score (AI)
8.2
/ 10.0
🔧 Remediation Steps (English)
IMMEDIATE ACTIONS:
1. Identify all systems running X.Org X server or Xwayland using: ps aux | grep -E 'X|Xwayland' and package managers (rpm -qa | grep xorg-x11-server)
2. Restrict X server access to trusted networks only; disable remote X11 forwarding if not required
3. Implement SSH X11 forwarding restrictions in /etc/ssh/sshd_config: set 'X11Forwarding no' for non-essential users
PATCHING GUIDANCE:
1. Apply vendor patches immediately for RHEL 7/8/9/10 via: yum update xorg-x11-server xwayland
2. For other distributions, check vendor advisories and apply available patches
3. Test patches in non-production environments before deployment
COMPENSATING CONTROLS (if patching delayed):
1. Run X server with reduced privileges (non-root user) where possible
2. Implement SELinux policies restricting X server capabilities
3. Use AppArmor profiles to limit buffer overflow exploitation
4. Deploy network segmentation to restrict X11 protocol access (TCP port 6000-6063)
DETECTION RULES:
1. Monitor for X server crashes: grep 'X server terminated' /var/log/Xvfb.log
2. Alert on keyboard type index values exceeding 255 in X protocol traffic
3. Monitor for privilege escalation attempts following X server restarts
4. Implement IDS signatures for malformed XKB protocol messages
🔧 خطوات المعالجة (العربية)
الإجراءات الفورية:
1. تحديد جميع الأنظمة التي تقوم بتشغيل خادم X.Org أو Xwayland باستخدام: ps aux | grep -E 'X|Xwayland' ومديري الحزم
2. تقييد وصول خادم X إلى الشبكات الموثوقة فقط؛ تعطيل إعادة توجيه X11 البعيد إذا لم يكن مطلوباً
3. تنفيذ قيود إعادة توجيه X11 في SSH في /etc/ssh/sshd_config
إرشادات التصحيح:
1. تطبيق تصحيحات البائع فوراً لـ RHEL 7/8/9/10 عبر: yum update xorg-x11-server xwayland
2. بالنسبة للتوزيعات الأخرى، تحقق من تنبيهات البائع وطبق التصحيحات المتاحة
3. اختبر التصحيحات في بيئات غير الإنتاج قبل النشر
الضوابط البديلة:
1. تشغيل خادم X بامتيازات منخفضة (مستخدم غير جذر) حيث أمكن
2. تنفيذ سياسات SELinux لتقييد قدرات خادم X
3. استخدام ملفات تعريف AppArmor لتحديد استغلال تجاوز المخزن المؤقت
4. نشر تقسيم الشبكة لتقييد وصول بروتوكول X11
قواعد الكشف:
1. مراقبة توقف خادم X
2. تنبيهات لقيم فهرس نوع لوحة المفاتيح التي تتجاوز 255
3. مراقبة محاولات تصعيد الامتيازات بعد إعادة تشغيل خادم X
4. تنفيذ توقيعات IDS لرسائل بروتوكول XKB المشوهة
📋 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.8.1.1 - Information Security Awareness
ECC 2024 A.12.2.1 - Change Management
ECC 2024 A.12.6.1 - Management of Technical Vulnerabilities
🔵 SAMA CSF
SAMA CSF ID.BE-1 - Asset Management
SAMA CSF PR.DS-6 - Data Security
SAMA CSF PR.IP-12 - Security Patch Management
SAMA CSF DE.CM-8 - Vulnerability Scanning
SAMA CSF RS.MI-2 - Incident Response and Recovery
🟡 ISO 27001:2022
ISO 27001:2022 A.5.23 - Information Security for Supplier Relationships
ISO 27001:2022 A.8.1 - User Endpoint Devices
ISO 27001:2022 A.12.6.1 - Management of Technical Vulnerabilities
ISO 27001:2022 A.14.2.1 - Secure Development Policy
🟣 PCI DSS v4.0.1
PCI DSS 6.2 - Security Patches and Updates
PCI DSS 11.2 - Vulnerability Scanning
🔗 References & Sources 5
🔗
https://access.redhat.com/security/cve/CVE-2026-50259
secalert@redhat.com
Third Party Advisory
🔗
https://bugzilla.redhat.com/show_bug.cgi?id=2485384
secalert@redhat.com
Issue Tracking
Third Party Advisory
🔗
https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eac...
secalert@redhat.com
Patch
🔗
https://lists.x.org/archives/xorg-announce/2026-June/003702.html
secalert@redhat.com
Mailing List
Third Party Advisory
🔗
https://redhat.atlassian.net/browse/PSIRTSUPT-16950
secalert@redhat.com
Permissions Required
📦 Affected Products / CPE 6 entries
x.org:x_server
x.org:xwayland
redhat:enterprise_linux:7.0
redhat:enterprise_linux:8.0
redhat:enterprise_linux:9.0
redhat:enterprise_linux:10.0