Ahead by 9.7sec after winning stage 11, Vaher was 9.9 kilometres into the 13.05-kilometre Ängebäckstorp stage, SS12, when he suffered a high-speed spin into trees.
Vaher and co-driver Rait Jansen were uninjured but front and rear contact left their Toyota GR Yaris Rally2 with damage.
Teemu Suninen now leads the high-speed gravel event with a 4.8sec advantage ahead of Mikko Heikkilä with four stages remaining.
More to follow...