The COVID-19 list was created this summer for a player who either tests positive for or who has been quarantined after having been in close contact with an infected person or persons.
Players will remain on the list until they are medically cleared to return.
Littleton, 26, is a former undrafted free agent out of Washington signed by the Rams in 2016. He played out the final year of his three-year, $1,635 million contract before returning to the Rams last year on a one-year restricted deal worth $3,095,000.
The Raiders signed him as an unrestricted free agent this past March.
In 2020, Littleton has appeared in eight games for the Raiders and recorded 48 tackles and no sacks.