The Nigerian striker has struggled immensely since leaving CSKA for the King Power in 2016.
He has scored five goals in 33 appearances and has made only one start for the Foxes this season.
''Leicester and CSKA have agreed on the transfer of Musa. Ahmed will move to CSKA on loan until the end of the season,'' Musa's agent Tony Harris told Russian media.
''It remains for him to undergo a medical examination to complete the transfer. It will be held on January 29.''
With his team planning for the World Cup in June, Nigeria national team boss Gernot Rohr expressed his delight at the news Musa would be moving back to Russia.
"Musa is going back to Russia and it is very good news that he will be playing there," said the Super Eagles coach.
"Musa playing in Russia is a positive development so that we will have the sympathy of Russian fans
"This can be a good reason to get support from Russian fans because the people there like Musa."