No dates have yet been set for the hearings but both men are in danger of missing crucial Magners League ties over the festive period.
The Blues take on the Dragons at Rodney Parade on December 27 before hosting reigning champions the Ospreys on New Year's Eve and head coach Dai Young would dearly love to be able to call on two of his most consistent performers for the derby double.
Wales scrum-half Rees is alleged to have made contact with the eyes / eye area of Northampton Saints hooker Dylan Hartley during the first-half of the Pool 1 encounter at the Cardiff City Stadium.
The IRB's recommended sanction for the offence is as follows: Low End: 12 weeks; Mid Range: 18 weeks; Top End: 24+ weeks; Maximum: 156 weeks.
Former New Zealand No8 Rush was sent off in 55th minute of the same game for a dangerous tackle above the line of the shoulders on Northampton Saints lock Courtney Lawes.
His hearing will be held in Bristol and the independent Judicial Officer appointed for the hearing will be Christopher Quinlan (England).
A dangerous tackle carries the following penalties: Lower End: 2 weeks; Middle Range: 6 weeks; Top End: 10+ weeks; Maximum Sanction: 52 weeks.
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