function combineBuffers(buf1, buf2) {
  const result = Buffer.allocUnsafe(buf1.length + buf2.length);
  result.set(buf1, 0);
  result.set(buf2, buf1.length);
  return result;
}
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.