CVE-2021-20090 — AI Deep Analysis Summary

🚨 **Essence**: A **Path Traversal** flaw in the Buffalo WSR-2533DHPL2 router's web interface. <br>💥 **Consequences**: Attackers can bypass authentication and access restricted files/directories on the device.

🛡️ **Root Cause**: **Input Validation Error**. The web interface fails to properly sanitize directory traversal sequences (e.g., `../`) in user inputs.…

📦 **Affected Products**: <br>• **Buffalo WSR-2533DHPL2** (Firmware ≤ 1.02) <br>• **Buffalo WSR-2533DHP3** (Firmware ≤ 1.24) <br>🏭 **Vendor**: Buffalo (Japan).

🕵️ **Attacker Capabilities**: <br>• **Bypass Authentication**: Access the web interface without valid credentials. <br>• **Read Files**: Traverse directories to read sensitive system files or configurations.…

🔓 **Exploitation Threshold**: **LOW**. <br>• **Auth**: **Unauthenticated**. No login required. <br>• **Config**: Standard web interface access is sufficient. <br>• **Complexity**: Simple path traversal strings.

💣 **Public Exploits**: <br>• **PoC Available**: Yes. Nuclei templates and Awesome-POC repositories contain detection/exploitation scripts.…

🔍 **Self-Check Methods**: <br>1. **Nuclei Scan**: Use `nuclei-templates` for CVE-2021-20090. <br>2. **Manual Test**: Send HTTP requests with `../` sequences to web interface endpoints. <br>3.…

🩹 **Official Fix**: <br>• **Patch**: Update firmware to **> 1.02** (for DHPL2) or **> 1.24** (for DHP3). <br>• **Status**: Vendor has released updates to address the input validation flaw.

🚧 **No Patch Workaround**: <br>1. **Block Access**: Restrict web interface access via firewall rules (only allow trusted IPs). <br>2. **Disable HTTP**: If possible, disable the vulnerable web management interface.…

⚠️ **Urgency**: **HIGH**. <br>• **Active Threat**: Actively exploited in the wild. <br>• **Impact**: Complete bypass of web authentication.…