For the soft fork to be activated in Bitcoin Core, it requires at least 95 percent of hashpower from miners to active it. (bitcoinmagazine.com)
This was complemented by a miners vote with hashpower where an attempt at manipulation was instantly obvious and therefore had no effect. (ccn.com)
A «51 % attack» could theoretically allow an entity that gained more than 50 % of bitcoin's total network hashpower to double - spend bitcoins, reverse transactions and prevent block confirmations. (coindesk.com)