CVE-2021-40346 — AI Deep Analysis Summary

🚨 **Essence**: HAProxy has an input validation error in `htx_add_header()` and `htx_add_trailer()`.…

🔍 **Root Cause**: **Integer Overflow** leading to insufficient input validation. <br>🛑 **Flaw**: The functions fail to check the length of header names properly.…

🏢 **Vendor**: HAProxy (HAProxy Technologies). <br>📦 **Product**: HAProxy (Open-source TCP/HTTP Load Balancer). <br>📅 **Affected**: Versions prior to the fix released around **September 2021**.…

💀 **Attacker Actions**: <br>1. **Bypass Security Rules**: Access restricted paths (e.g., `/admin`) that HAProxy explicitly denies. <br>2.…

⚡ **Threshold**: **Low**. <br>🔓 **Auth**: No authentication required. <br>⚙️ **Config**: Exploits the core parsing logic of HAProxy. <br>🎯 **Ease**: Simple HTTP requests can trigger the integer overflow.…

🔥 **Public Exploits**: **YES**. <br>📂 **PoCs**: Multiple GitHub repositories exist (e.g., `knqyf263/CVE-2021-40346`, `donky16/CVE-2021-40346-POC`).…

🔎 **Self-Check**: <br>1. **Scan**: Use tools detecting HAProxy version < 2.2.17 (or patched version). <br>2. **Test**: Send crafted headers with specific length patterns to trigger integer overflow. <br>3.…

🛡️ **Official Fix**: **YES**. <br>📝 **Patch**: HAProxy released a fix (Commit `3b69886f...`). <br>📢 **Advisory**: Fedora and other distros issued updates (e.g., `FEDORA-2021-cd5ee418f6`).…

🚧 **No Patch Workaround**: <br>1. **WAF**: Deploy a Web Application Firewall to filter malformed headers. <br>2.…

🔴 **Urgency**: **HIGH**. <br>⚠️ **Priority**: Critical. <br>📉 **Impact**: Allows bypassing access controls and potential data injection. <br>🚀 **Recommendation**: Patch immediately.…