CVE-2016-10555 — AI Deep Analysis Summary

🚨 **Essence**: A critical flaw in `jwt-simple` (Node.js JWT module) allows **algorithm confusion**.…

🛡️ **Root Cause**: **CWE-20** (Improper Input Validation).…

📦 **Affected**: `jwt-simple` Node.js module. 📅 **Versions**: **0.3.0 and earlier**. 🏷️ **Vendor**: Associated with HackerOne reports and the `hokaccha` GitHub repository.

💀 **Attacker Capabilities**: Can **forge arbitrary JWT tokens**. 🔄 **Privileges**: Bypasses signature verification by using the server's public key as the HMAC secret.…

⚡ **Threshold**: **Low**. 🌐 **Config**: Requires the application to use RS256 (asymmetric) but the library incorrectly accepts HS256 (symmetric) verification using the public key.…

🔓 **Public Exp?**: **Yes**. Multiple PoCs exist on GitHub (e.g., `CircuitSoul/poc-cve-2016-10555`, `Venom-JWT`). Tools like `jwt_tool` and custom Python scripts are available to demonstrate the RS256→HS256 switch.

🔍 **Self-Check**: Scan for `jwt-simple` dependency in `package.json`. Check if version ≤ 0.3.0. 🔎 **Feature**: Look for JWT implementations using RS256 that might inadvertently accept HS256 signatures during testing.

🩹 **Fixed?**: **Yes**. Official patches were merged via GitHub Pull Requests (#14, #16) to `hokaccha/node-jwt-simple`. 📢 **Reference**: NodeSecurity advisories and Auth0 blog posts confirm the vulnerability and fix.

🚧 **No Patch Workaround**: **Strictly validate the `alg` header**. Ensure the verification code explicitly rejects HS256 if RS256 is expected.…

🔥 **Urgency**: **HIGH**. ⚠️ **Priority**: Immediate action required for legacy systems. This is a well-known, easily exploitable authentication bypass.…