Centre-back Flint arrived in the Welsh capital in July 2019, signing a three-year contract with the Bluebirds.
The thirty-year old defender began his professional career at Swindon Town, before moving to Bristol City in 2013. Aden spent five years at Ashton Gate, helping the Robins to become winners of League One and the EFL Trophy in 2014-15.
Flint joined Middlesbrough in 2018, making twenty-two appearances at the Riverside Stadium before making the move to South Wales ahead of the 2019-20 season.
An imposing aerial presence, Aden has recorded an impressive goal tally despite his position as a defender. He netted fifteen goals in the 2014-15 season, including a hat-trick against Walsall, with forty-eight career strikes in total.