Millenic Alli sparked a late fightback (Rhianna Chadwick/PA)
Exeter scored twice in the final eight minutes to earn a point as Leyton Orient were forced to play out the final stages with 10 men due to Brandon Cooper’s injury.
Ollie O’Neill and George Moncur scored for the hosts but the Grecians salvaged a point through Millenic Alli and Will Aimson.
The deadlock was broken in the 36th minute by O’Neill, who scored direct from a corner on the left when his set-piece delivery eluded everyone in a crowded penalty area and found the far corner of the net.
The Os doubled their lead in the 64th minute when O’Neill intercepted an intended clearance and fed unmarked substitute Moncur, who slotted the ball home from close range.
After Orient, having used all five substitutes, were reduced to 10 men by the loss of Cooper, Exeter camped in and around the opposition penalty area and reduced the deficit when substitute Alli headed home on 88 minutes.
Four minutes later, Aimson got the final touch on Tommy Carroll’s shot to salvage a point.
