The 22-year-old Scotland striker made his switch to the City Ground last summer but found himself sidelined by Mark Warburton during the final days of his Forest reign.
The Light Blues are now rumoured to be considering offering him an escape route back north of the border.
A fee of around B£1million would be required to prise him away but Ibrox boss Graham Murty now has room to manoeuvre after striking a deal with Mexican outfit Cruz Azul – now managed by his Light Blues predecessor Pedro Caixinha – that will see them cover all of Carlos Pena’s B£20,000-a-week wages as part of a six-month loan deal, with a guaranteed B£2million sum to follow if the move is made permanent.
However, Press Association Sport understands Cummings is not ready to walk away from Forest just six months after signing on from Hibernian.
He is willing to bide his time while Karanka, who was handed a two-and-a-half-year deal by Forest chiefs on Monday, assesses his new squad in the hope he can make a bigger impact under the former Middlesbrough boss than he managed with ex-Gers manager Warburton.
While Pena has agreed terms with Cruz Azul, Press Association Sport understands that two of his fellow Caixinha recruits – Fabio Cardosso and Eduardo Herrera – will only be allowed to move themselves if they can find clubs also willing to pay their salaries in full.
Meanwhile, new Rangers signing Jamie Murphy believes his best is yet to come after signing for his boyhood heroes.
The Brighton attacker sealed a six-month loan switch with the Light Blues over the weekend with a permanent deal set to be concluded this summer.
He has now met up with his new team-mates after flying out to America, where the Ibrox side are competing in the Florida Cup.
The 28-year-old told RangersTV: “I’m delighted to be here. Obviously it lasted a couple of days, the transfer, but I’m glad everything went through.
“The last couple of days were a bit manic but to get everything done and to come over and see all the boys, it’s been a great start.
“Rangers is obviously the team I supported growing up and the team my family supported as well so they are all delighted, as am I, and I can’t wait to play some football.
“I feel the best years are obviously ahead of me. I’ve had a good career up until now, obviously down in England and in Scotland, so I’m looking to kick on, as Rangers are. Everything is looking up.
“There was a little tear in my dad’s eye when we were doing all the signing stuff so it’s a big thing.
“Obviously being from Glasgow I know what it’s like supporting the club, so I’m going to do everything I can to try and help Rangers become successful again.”
Watford are being linked with a summer swoop for Werder Bremen's Sweden international left-back Ludwig Augustinsson.