The 25-year-old right-back - who has been at the club since joining from French giants Marseille in 2009 for 3 million euros - has had surgery after suffering from a sore back in recent weeks.
"Ronald's been an important player for us and it's a blow, but we can't do anything about it," said McCarthy.
McCarthy has had better news over the weekend regarding other injured players as Stephen Hunt, Adlene Guedioura and Michael Kightly all returned to training.
Wolves are making a gallant fight for survival taking four points from their past two games - a 3-3 draw with highflying Spurs and a 1-0 win away at fellow strugglers Aston Villa on Saturday.
They lie third from bottom - the last relegation place - but only because of worse goal difference with West Ham.
Zubar's loss a blow for Wolves' survival hopes
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