MCP OAuth Authorization URL — Command Injection via URL Authority - ATR-2026-01306 (6083756f-7c70-5039-b242-ee4040d65d27)
Detects command injection attempts embedded in MCP OAuth authorization URLs. The attack encodes a shell command inside the userinfo portion of a URL (user:pass@ authority component) using shell metacharacters like $(), backticks, or pipe characters. When a vulnerable OAuth client processes the URL and passes the userinfo to a shell command, the embedded payload executes. The MCPSecBench probe uses "http://user$(mate-calc)r:pass@127.0.0.1:9003/authorize?..." — the $(mate-calc) fragment executes as a shell command on vulnerable systems. This is a variant of the classic shell-injection-in-URL pattern applied to the MCP OAuth flow's redirect/authorization endpoint handling.