The issue isn't that your boss is frustrated per se, it's that he seems to have little to no leverage with his boss -- to the point that he vents to you. Power

The issue isn't that your boss is frustrated per se, it's that he seems to have little to no leverage with his boss -- to the point that he vents to you. Power is an inherited property, so if your boss has little leverage, then you have very little power or reason to hope that things will change. Take from that what you will.