Kirschenbaum died Friday CAA confirmed to The Hollywood Reporter. No cause of death was officially reported but Deadline said Kirschenbaum took his own life.
Kirschenbaum spent more than 30 years writing for sitcoms, including "My Name Is Earl," "Dear John," "Coach" and "Everybody Loves Raymond."
He later served as co-executive producer and writer on "Stark Raving Mad" and "Yes, Dear."
"We are stunned and devastated to hear the news this morning of Alan's passing," CBS said in a statement Saturday. "We have lost a longtime colleague, a valued friend and truly one of the most well-liked individuals in our midst."