His Boro side headed into the international break on the back of a 2-0 Championship loss at Hull, with the defeat compounded by the sight of key centre-half Dael Fry leaving the fray late on with injury, with the Tigers scoring two goals in his absence.
Fellow defender Grant Hall was also unavailable for the game at Hull after sustaining a thigh problem in training on Friday, while Lee Peltier picked up a fifth booking of the season at the MKM Stadium, which rules him out of Boro's next home game with Peterborough United on October 16.
With Anfernee Dijksteel and Darnell Fisher also out injured, Boro's options at the back are getting seriously thin, while summer midfield signing Martin Payero has also been struggling with injury niggles since his arrival, with Marcus Browne also sidelined.
Warnock, who has been linked with a move for former Burnley player Robbie Brady, has two spaces left to fill in his 25-man Championship squad and says that the club - handed by - are scouring free agent options.
Championship clubs can only register 25 players over the age of 21 in their squads. Loan players or players aged under 21 do not count towards that limit.
Warnock, who named just six subs at Hull, said: "I have two spaces in the squad so if we put somebody over 21 (on the bench), that takes a space up. There still might be free transfers that Kieran is looking at.
"If we could bring one or two in, we might do that, but it's not easy.
"We are looking at players who are out of contract who are not fixed up yet. The problem with that is are they going to be fit enough to come in and start from day one. It's catch-22, really. I am not sure what we will come up with, but we will have to come up with something in the two weeks we have got.
"It is not easy to see if any of the injured lads will be back for Peterborough and the lads are going to their international. If Paddy (McNair) comes back and is injured, then we are 'cream crackered.'
"It looks very bleak regarding injuries, but I will come up with something for the next game. Although I don't think there are too many under-23s I can bring in."
On the situation with Fry and Hall, he added: "He got a smashed arm in his face, which unfortunately nobody saw. The referee was in a poor position and the fourth official saw it, I am sure.
"I thought it could easily have been a red card, having watched it back. He got up too quickly and tried to tackle and pulled his stomach or groin and cannot move after that.
"By Monday, we should have an idea. Knowing our luck, it will be three months."
And on Hall, he added: "A ball hit him and he reacted quickly and I think he has pulled a thigh muscle or something like that. That was in the last minute of the training session (on Friday)."