Answered by Shaykh Faraz Rabbani
Question: Is it required that one shave the hair between the buttocks? Is that considered pubic hair?
Answer: In the name of Allah, Most Merciful.
The pubic hair that one is expected to remove refers to the front private areas.
As for removing the hair between the buttocks, this is recommended, as it prevents filth (najasa) from getting stuck there, and is more clean. [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah]