Matthias Walkner (KTM) and Joan Barreda (Honda) completed the top five on the stage provisionally, but with both Brabec and Sunderland both set to gain time back.
As things stand, Cornejo is now 11 minutes and 24 seconds clear of Benavides at the head of the general classification with three stages left to run, giving him by some distance the largest lead any rider has enjoyed of the rally so far.
Barreda has moved up to a provisional third, exactly 29 minutes back, but is set to fall behind Sunderland and Brabec once the times are finalised.
KTM rookie Daniel Sanders is likely to be sixth overall ahead of privateer Skyler Howes (KTM) and Sherco rider Lorenzo Santolino.
Yamaha's miserable luck continued as Ross Branch - already outside of the top 10 owing to his earlier problems - was forced out of the event with engine trouble, leaving van Beveren as the manufacturer's sole remaining factory representative in ninth.