All three goals came in an astonishing 13 minute spell in the first half and although Nicky Law pulled one back for Ally McCoist’s side, Hibs held firm to claim a victory which catapulted them from ninth place to fifth in the table.
And Hearts, too, were cheering their Capital rivals, the result leaving the Gorgie outfit sic points clear at the top.
Former Hibs star Dean Shiels almost inflicted the first wound on his old club, the Northern Ireland internationalist drilling a low shot under the defensive wall from 22 yards after Paul Hanlon had clumsily brought down Kris Boyd.
But goalkeeper Mark Oxley was alert to the danger, diving low to his right to push the ball to a safe area where it was booted clear.
Rangers, as to be expected, enjoyed the lion’s share of possession although Hibs head coach Alan Stubbs would probably have reflected that his side hadn’t made the most of it when they were on the ball - that was until the 25th minute when Cummings opened the scoring.
The teenager was strong enough to hold off Arnold Peralta as the pair battled for Oxley’s mammoth clearance and managed to squeeze the ball under the body of Rangers goalkeeper Steve Simonsen, his shot carrying enough weight to take it into the net despite the desparing efforts of Peralta to stop it crossing the line.
And it got even better for Hibs six minutes later when Gray got goalside of ex-Hearts defender Lee Wallace to meet Lewis Stevenson’s cross, the former Manchester City trainee directing a powerful header down into the turf, the ball rearing up and into the roof of Simonsen’s net.
Unbelievably, Hibs got a third in the 38th minute, Dominique Malonga and Stevenson combining to set up Cummings for his second goal of the game, the youngster coolly slotting a low angled shot beyond Simonsen.
Law threw Rangers a lifeline as he pulled one back ten minutes into the second half, the midfielder coolly sidefooting the ball high into the net from 20 yards as he latched onto Forster’s headed clearance.
Rangers threw everything at Hibs as the clock ticked down, but the Edinburgh outfit held firm to claim their first win at Ibrox since November, 2011, when goals from Liam Miller, John Rankin and Francis Dickoh gave Colin Calderwood his first win as manager.
Rangers: Simonsen, McGregor, McCulloch, Mohsni, Wallace, Peralta (Aird 46), Black, Law, Smith (Templeton 69), Boyd, Shiels (Daly 64).
Subs not used: Robinson, Zaliukas, Foster. Hutton.
Hibs: Oxley, Forster, Fontaine, Hanlon, Gray (Booth 46), S Allan, Robertson, Craig, Stevenson, Malonga, Cummings (Harris 80).
Subs not used: Perntreou, Stanton, Heffernan, Handling, Kennedy.
Referee: Calum Murray.