The Longhorns' staff will meet Monday to determine Foster's immediate future with the program after the safety reportedly quit during the third quarter of Saturday's win over UTEP.
Foster was apparently upset about his lack of playing time in the contest.
The 2018 five-star recruit is the No. 12-ranked player on the ESPN 300 and the top safety in his class.
Foster played in nine games a season ago, totaling 35 tackles, 2.5 sacks, and one interception.
The junior defensive back suffered a broken hand in June after punching a car but was able to return for voluntary workouts in August.