The Wales international left Selhurst Park on crutches after he was injured in a 1-1 Premier League draw with Crystal Palace last week.
Carver said on Thursday that Dummett does not require surgery, but the 23-year-old faces a battle to return before the end of the season.
He said at a press conference: "The good news is Paul Dummett doesn't need an operation, but he is out for around 10-12 weeks."
Dummett has made 21 appearances for the Tyneside club this season and his absence leaves Carver facing a shortage of options in defence.
Fabricio Coloccini, Daryl Janmaat, Mike Williamson and Massadio Haidara are the only senior defenders still available for selection.
Steven Taylor is out for the season, while Mapou Yanga-Mbiwa and Davide Santon were loaned to Serie A sides Roma and Inter respectively.
Carver will have to hope that there are no further injury blows or suspensions to his four fit defenders between now and the end of the season, although Vurnon Anita is capable of covering at full-back.
Newcastle face a daunting trip to champions Manchester City on Saturday.
