CVE-2020-13935 — AI Deep Analysis Summary

🚨 **Essence**: Apache Tomcat WebSocket module fails to validate payload lengths correctly. 💥 **Consequences**: Triggers an **infinite loop** during frame processing, leading to a **Denial of Service (DoS)**.…

🛡️ **Root Cause**: Lack of proper validation for **WebSocket frame payload length**. 🔍 **CWE**: Not explicitly listed in data, but technically relates to **Input Validation** failures leading to resource exhaustion.

📦 **Affected Products**: Apache Tomcat. 📅 **Affected Versions**: • 10.0.0-M1 to 10.0.0-M6 • 9.0.0.M1 to 9.0.36 • 8.5.0 to 8.5.56 • 7.0.27 to 7.0.104

👮 **Attacker Action**: Send multiple malicious requests with invalid payload lengths. 📉 **Impact**: Causes **DoS** (Service Down). ⚠️ **Privileges**: No code execution or data theft mentioned; purely availability impact.

🔓 **Threshold**: **Low**. ⚙️ **Config**: Requires access to the WebSocket endpoint. 🚫 **Auth**: No authentication required to exploit the logic flaw itself, just network reachability to the WS port.

💻 **Public Exploit**: **YES**. 📂 **Resources**: GitHub repos like `RedTeamPentesting/CVE-2020-13935` provide `tcdos` binary. 🚀 **Status**: Wild exploitation is possible via simple Go-based tools.

🔍 **Self-Check**: Use the `tcdos` tool against your WebSocket endpoints. 📡 **Scanning**: Nuclei templates (`CVE-2020-13935.yaml`) available for automated detection.…

🩹 **Official Fix**: **YES**. Oracle/Oracle Linux advisories (USN-4448-1) and Debian LTS updates confirm security patches are available. 🔄 **Action**: Upgrade to non-vulnerable versions immediately.

🚧 **No Patch Workaround**: 1. **Firewall**: Block external access to WebSocket ports if possible. 2. **WAF**: Configure rules to drop malformed WebSocket frames. 3.…

🔥 **Urgency**: **HIGH**. ⚡ **Priority**: Critical for availability. Since public exploits exist and it causes DoS, patch immediately or apply network-level mitigations. Don't wait!