Summers was hired under former Buffaloes coach Mel Tucker in December 2018, and was one of the staff members retained by current Colorado coach Karl Dorrell.
Summers is due around $500,000, which could be lowered if he finds another position.
The Buffaloes allowed 420.3 yards per game and 31.7 points last season as they finished 4-2. The team lost to Texas 55-23 in the Alamo Bowl.
Before his arrival in Boulder, Summers was a defensive analyst for quality control at Georgia. Among his other previous roles were head coach at Georgia Southern, along with stints as defensive coordinator at Colorado State and Central Florida.