CVE-2020-29390 — AI Deep Analysis Summary

Q: Who is affected? (Versions/Components)

📦 **Affected**: Zeroshell Linux distribution. 📌 **Version**: Specifically **3.9.3**. 🌐 **Context**: Used in servers and embedded systems (often routers).

Q: Is exploitation threshold high? (Auth/Config)

⚡ **Threshold**: **LOW**. 🔓 **Auth**: None needed. ⚙️ **Config**: Exploitable via standard HTTP requests to the CGI endpoint. Highly accessible.

Q: Is there a public Exp? (PoC/Wild Exploitation)

🔓 **Public Exp?**: **YES**. 📜 **PoC**: Available via Nuclei templates (ProjectDiscovery). 🌍 **Wild Exp**: High risk due to simplicity and lack of auth.

Q: How to self-check? (Features/Scanning)

🔍 **Self-Check**: Scan for `/cgi-bin/kerbynet` endpoint. 🧪 **Test**: Send payload with shell metacharacters (`;`, `|`) and `%0a` in `StartSessionSubmit`. Check for command output in response.

Q: Is it fixed officially? (Patch/Mitigation)

🩹 **Fix**: Update Zeroshell to a patched version (if available from vendor). 📝 **Note**: Vendor info marked 'n/a' in data, so check official Zeroshell channels for specific patch releases post-2020-11-30.

Q: Is it urgent? (Priority Suggestion)

🔥 **Urgency**: **CRITICAL**. ⏱️ **Priority**: Immediate action required. Unauthenticated RCE is a top-tier threat. Patch or isolate affected devices NOW.

Updated May 08, 2026

This is a summary of the AI-generated 10-question deep analysis. The full version (longer answers, follow-up Q&A, related CVEs) requires login. Read the full analysis →

Q1What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: A critical OS Command Injection flaw in Zeroshell. <br>💥 **Consequences**: Attackers can execute arbitrary system commands remotely.…

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Q2Root Cause? (CWE/Flaw)

🛡️ **Root Cause**: Improper input validation in the `cgi-bin/kerbynet` module.…

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Q3Who is affected? (Versions/Components)

📦 **Affected**: Zeroshell Linux distribution. <br>📌 **Version**: Specifically **3.9.3**. <br>🌐 **Context**: Used in servers and embedded systems (often routers).

Q4What can hackers do? (Privileges/Data)

💀 **Privileges**: **Unauthenticated** access. No login required. <br>📂 **Data**: Full system command execution.…

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Q5Is exploitation threshold high? (Auth/Config)

⚡ **Threshold**: **LOW**. <br>🔓 **Auth**: None needed. <br>⚙️ **Config**: Exploitable via standard HTTP requests to the CGI endpoint. Highly accessible.

Q6Is there a public Exp? (PoC/Wild Exploitation)

🔓 **Public Exp?**: **YES**. <br>📜 **PoC**: Available via Nuclei templates (ProjectDiscovery). <br>🌍 **Wild Exp**: High risk due to simplicity and lack of auth.

Q7How to self-check? (Features/Scanning)

🔍 **Self-Check**: Scan for `/cgi-bin/kerbynet` endpoint. <br>🧪 **Test**: Send payload with shell metacharacters (`;`, `|`) and `%0a` in `StartSessionSubmit`. Check for command output in response.

Q8Is it fixed officially? (Patch/Mitigation)

🩹 **Fix**: Update Zeroshell to a patched version (if available from vendor). <br>📝 **Note**: Vendor info marked 'n/a' in data, so check official Zeroshell channels for specific patch releases post-2020-11-30.

Q9What if no patch? (Workaround)

🚧 **Workaround**: <br>1. **Block Access**: Restrict access to `/cgi-bin/kerbynet` via firewall/WAF. <br>2.…

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Q10Is it urgent? (Priority Suggestion)

🔥 **Urgency**: **CRITICAL**. <br>⏱️ **Priority**: Immediate action required. Unauthenticated RCE is a top-tier threat. Patch or isolate affected devices NOW.

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