McCarthy has played just twice for Palace this season, with both of those appearances coming at the start of the season in the Capital One Cup.
It seems that Alan Pardew has decided that McCarthy's future lies elsewhere and Bolton have sensed their opportunity to add him to their ranks.
Neil Lennon has improved Wanderers considerably since taking over, but the former Celtic manager has been looking to add quality to his squad and is not afraid to bring in veterans.
The likes of Emile Heskey and Eidur Gudjohnsen have already been brought in by Lennon and McCarthy would push the average age of Bolton’s squad up even further if he did sign.
The 31-year-old centre-back has already been on loan once this season to League One Sheffield United and Lennon evidently feels that he still has enough quality to cope at a higher level.