According to the search results, the ranking of the Colorado Buffaloes football team varies depending on the source and the date. Here are the rankings found:

• September 5, 2023: No. 22 in the AP Top 25 poll
• September 17, 2023: No. 19 in the AP Top 25 poll
• September 22, 2023: Not ranked in the AP Top 25 poll
• September 22, 2023: No. 42 in the FBS (Overall) ranking
• September 24, 2023: No. 8 USC is ranked and will play against Colorado

Therefore, as of September 24, 2023, the Colorado Buffaloes football team is not ranked in the AP Top 25 poll, but they will play against the No. 8 USC Trojans.