Read was penalised for his dangerous tackle in the All Blacks 63-0 victory in Oita on Wednesday night. Referee Romain Poite initially missed the incident but would later give Canada the penalty advantage after his fellow official spotted the tackle.
The citing commissioner had 36 hours to review the incident but that time has now expired.
Under World Rugby's current high tackle framework, Read's shot could have been considered a high tackle because of the possible contact with either the head or neck. The tackle then could be deemed worthy of either a red or a yellow card depending on the "degree of danger".
The decision has prompted claims of All Black favouritism some places.
Earlier in the tournament, Wallaby Reece Hodge was banned for three games for a tackle on Fiji's Peceli Yato. Like Read, Hodge's tackle wasn't deemed to be a red card on the day but the winger's tackle was referred to a judicial hearing.
The disciplinary committee "deemed that the incident was an act of foul play and warranted a red card in line with the high tackle sanction framework", World Rugby said in a statement.
It added that the tackle was "reckless, rather than deliberate", but contact with the head meant a high degree of danger.
Given Hodge's "exemplary disciplinary record, good character and conduct at the hearing", the committee reduced the six-match entry point by three matches.
In Hodge's case, Fiji referred the incident to the match's citing commissioner. (Teams have 12 hours post-match to refer any incident – which has passed in the case of the All Blacks.) However, the commissioner also has 36 hours to cite a player themselves for an act of foul play believed to warrant a red card.