Cash has become one of the Championship’s most sought-after players since Forest failed to secure promotion to the Premier League, and had attracted interest from Fulham, too.
Personal terms between Villa and Cash’s representatives have already been finalised.
Sheffield United previously had a £10m bid rejected for Cash, while West Ham had held an interest in the 23-year-old, who flourished at full-back under Sabri Lamouchi last season.
Villa are set for a proactive transfer window under new sporting director Johan Lange, with the club also attempting to negotiate deals for Brentford striker Ollie Watkins and Arsenal goalkeeper Emiliano Martinez.
Brentford’s capture of Ivan Toney from Peterborough is likely to accelerate Watkins’ departure, with a fee set to reach around £25m for the striker, who scored 26 goals in the Championship last season.
Villa have made Martinez their No 1 target in the goalkeeper’s position, but Arsenal are reluctant to sell the Argentine, who produced another impressive performance during the club’s Community Shield victory over Liverpool.
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