Critical Vulnerability in QWED-MCP: Arbitrary Code Execution via SymPy's parse_expr() Function
A critical vulnerability (CVE-2026-55546, CVSS score: 9.8) was discovered in QWED-MCP, a deterministic verification gateway for MCP, which allows an attacker to execute arbitrary operating-system commands, read or modify accessible data, exfiltrate process secrets, or reach internal services. The vulnerability exists in the verify_math_expression() function in src/qwed_mcp/engines/math_engine.py, which passes attacker-controlled input to SymPy's parse_expr() function without proper validation. Affected versions are prior to 0.2.1.