asteval is a Python expression evaluator designed for restricted execution. Prior to 1.0.9, in asteval/astutils.py, the default Interpreter with numpy enabled exposes a ctypes type and permits fromaddress memory access. safegetattr blocks the ctypes module but not reachable ctypes type objects, while attribute assignments use unfiltered setattr instead of safesetattr. An attacker-controlled expression can derive an address with id, read memory through fromaddress, and write through an attribute assignment. The expression can read or corrupt arbitrary process memory, escape the intended sandbox, execute code, disclose secrets, or crash the host process. This issue is fixed in version 1.0.9.