Robert Lewandowski is Bayern's only fit striker at present and has expressed his frustration on a number of occasions that players have not been drafted in to ease his workload.
Lewandowski – who has 11 goals in as many league games this season – was criticised by Bayern CEO Karl-Heinz Rummenigge for airing his concerns, but they appear to have been acted on.
Anthony Modeste, Kasper Dolberg and Timo Werner have all been linked with the reigning champions but Wagner – who began his career with Bayern – appears most likely to make the move to the Allianz Arena.
"If you are interested in a player who has a contract, you have to go directly to the club, " the veteran coach told a news conference.
"Hasan Salihamidzic [Bayern's sporting director] has spoken to [Hoffenheim sporting director] Alexander Rosen about the possibility of a transfer,
"This is the phase we are in, no further. He has developed well [since leaving Bayern]."
Wagner has scored six goals in all competitions for Hofffeinheim this season having netted on 11 occasions last season as Julian Nagelsmann's side finished fourth in the Bundesliga table.