📄 Description (English)
A security vulnerability has been detected in Tenda A21 1.0.0.0. This vulnerability affects the function set_device_name of the file /goform/setBlackRule of the component MAC Filtering Configuration Endpoint. Such manipulation of the argument devName/mac leads to stack-based buffer overflow. The attack may be performed from remote. The exploit has been disclosed publicly and may be used.
🤖 AI Executive Summary
A critical stack-based buffer overflow vulnerability exists in Tenda A21 router firmware (v1.0.0.0) affecting the MAC filtering configuration endpoint. Remote attackers can exploit this vulnerability without authentication to execute arbitrary code or cause denial of service. With public exploit availability and widespread router deployment in Saudi networks, immediate patching is essential.
📄 Description (Arabic)
🤖 AI Intelligence Analysis Analyzed: Apr 22, 2026 22:59
🇸🇦 Saudi Arabia Impact Assessment
High impact on Saudi telecommunications infrastructure (STC, Mobily, Zain networks), government agencies, and enterprise networks relying on Tenda A21 routers for network segmentation and access control. Banking sector at risk if routers used in branch networks. Healthcare facilities using these routers for network isolation vulnerable to lateral movement attacks. ARAMCO and critical infrastructure operators may face operational disruption. SMEs and residential users in Saudi Arabia represent significant attack surface.
🏢 Affected Saudi Sectors
Telecommunications (STC, Mobily, Zain)
Banking and Financial Services
Government and Public Administration
Healthcare
Energy and Utilities (ARAMCO)
Critical Infrastructure
Small and Medium Enterprises
Residential/Consumer Networks
🎯 MITRE ATT&CK Techniques
⚖️ Saudi Risk Score (AI)
8.9
/ 10.0
🔧 Remediation Steps (English)
IMMEDIATE ACTIONS:
1. Identify all Tenda A21 devices in your network using network scanning tools (nmap, Shodan queries for Saudi IP ranges)
2. Isolate affected devices from critical network segments if immediate patching is not possible
3. Disable remote management features on affected routers
4. Implement network segmentation to limit router access to trusted administrative networks only
PATCHING GUIDANCE:
1. Check Tenda's official website for firmware version > 1.0.0.0
2. Download firmware only from official Tenda sources to avoid supply chain attacks
3. Perform firmware updates during maintenance windows with documented change control
4. Verify firmware integrity using MD5/SHA checksums provided by Tenda
5. Test in lab environment before production deployment
COMPENSATING CONTROLS (if patch unavailable):
1. Implement firewall rules blocking access to /goform/setBlackRule endpoint from untrusted networks
2. Deploy IDS/IPS signatures detecting buffer overflow attempts to MAC filtering endpoints
3. Monitor router logs for suspicious setBlackRule requests with oversized devName/mac parameters
4. Restrict router administrative access to specific IP ranges using ACLs
5. Implement network-based rate limiting on router management ports (80, 443, 8080)
DETECTION RULES:
1. Monitor HTTP POST requests to /goform/setBlackRule with devName or mac parameters exceeding 256 bytes
2. Alert on multiple failed authentication attempts to router management interface
3. Track firmware version changes on Tenda A21 devices
4. Monitor for unusual process execution on router (if accessible via SSH)
5. Implement YARA rules for known Tenda A21 exploit payloads
🔧 خطوات المعالجة (العربية)
الإجراءات الفورية:
1. تحديد جميع أجهزة Tenda A21 في شبكتك باستخدام أدوات المسح (nmap، استعلامات Shodan للنطاقات السعودية)
2. عزل الأجهزة المتأثرة عن القطاعات الحرجة إذا لم يكن التصحيح الفوري ممكنًا
3. تعطيل ميزات الإدارة البعيدة على الموجهات المتأثرة
4. تنفيذ تقسيم الشبكة لتحديد وصول الموجه للشبكات الإدارية الموثوقة فقط
إرشادات التصحيح:
1. تحقق من موقع Tenda الرسمي للحصول على إصدار ثابت > 1.0.0.0
2. قم بتنزيل البرنامج الثابت من مصادر Tenda الرسمية فقط
3. قم بإجراء تحديثات البرنامج الثابت خلال نوافذ الصيانة
4. تحقق من سلامة البرنامج الثابت باستخدام MD5/SHA
5. اختبر في بيئة معملية قبل النشر الإنتاجي
الضوابط البديلة:
1. تنفيذ قواعد جدار الحماية لحظر الوصول إلى نقطة النهاية من الشبكات غير الموثوقة
2. نشر توقيعات IDS/IPS للكشف عن محاولات تجاوز المخزن المؤقت
3. مراقبة سجلات الموجه للطلبات المريبة بمعاملات حجم كبير
4. تقييد وصول الموجه الإداري إلى نطاقات IP محددة
5. تنفيذ تحديد معدل على منافذ إدارة الموجه
📋 Regulatory Compliance Mapping
🟢 NCA ECC 2024
ECC 2024 - 5.1.1: Vulnerability Management and Patch Management
ECC 2024 - 5.2.1: Network Security and Segmentation
ECC 2024 - 5.3.1: Access Control and Authentication
ECC 2024 - 6.1.1: Incident Detection and Response
🔵 SAMA CSF
SAMA CSF - ID.RA-1: Asset Management and Inventory
SAMA CSF - PR.IP-12: Software, Firmware, and Information Updates
SAMA CSF - DE.CM-1: Network Monitoring and Anomaly Detection
SAMA CSF - RS.MI-1: Incident Containment and Mitigation
🟡 ISO 27001:2022
ISO 27001:2022 - A.12.6.1: Management of technical vulnerabilities
ISO 27001:2022 - A.14.2.1: Secure development policy
ISO 27001:2022 - A.12.2.1: Monitoring and logging
ISO 27001:2022 - A.12.3.1: Protection against malware
🟣 PCI DSS v4.0.1
PCI DSS 4.0 - 6.2: Security patches and updates
PCI DSS 4.0 - 11.2: Vulnerability scanning and assessment
PCI DSS 4.0 - 1.1: Network segmentation
🔗 References & Sources 5
🔗
https://github.com/QIU-DIE/cve-nneeww/issues/3
cna@vuldb.com
Exploit
Issue Tracking
Mitigation
Third Party Advisory
🔗
https://vuldb.com/?ctiid.347109
cna@vuldb.com
Permissions Required
VDB Entry
🔗
https://vuldb.com/?id.347109
cna@vuldb.com
Third Party Advisory
VDB Entry
🔗
https://vuldb.com/?submit.754634
cna@vuldb.com
Third Party Advisory
VDB Entry
🔗
https://www.tenda.com.cn/
cna@vuldb.com
Product
📦 Affected Products / CPE 1 entries
tenda:a21_firmware:1.0.0.0