The py_sha3_new_impl function in sha3module.c has error handling code that looks like this: error: if (self) { Py_DECREF(self); } if (data && buf.obj) { PyBuffer_Release(&buf); } However, there is a `goto error` before the variable buf is initialized. If that error path is triggered, the function will attempt to free an invalid object, possibly leading to a program crash.