Salah, 25, injured his shoulder during Liverpool's Champions League final loss to Real Madrid on Saturday, prompting concerns he might miss the tournament.
But Egypt's national team doctor has met with Salah and in a subsequent tweet the country's FA said his absence "will not exceed" three weeks, according to a BBC report Thursday.
Egypt's opening World Cup fixture is against Uruguay on 15 June.
They meet hosts Russia on 19 June and conclude the group stage against Saudi Arabia on 25 June.
Salah also met with Egyptian FA president Hany Abu Rida on Wednesday.
"After the meeting of Abu Rida and the doctor of the national team in Spain today, the Football Association reaffirms Salah in the World Cup, God willing, will not exceed the absence of three weeks," the Egyptian FA tweeted on Wednesday.
Salah struck a 95th-minute penalty in the final qualification game to send Egypt to the World Cup for the first time in 28 years.
But in the Champions League final - the last fixture of a season in which he scored 44 goals for his club - he left the pitch in tears after landing heavily on his shoulder following a harsh challenge by Sergio Ramos.
At the time Liverpool boss Jurgen Klopp described the injury as "really serious".
However, the Egyptian FA has since said that Salah's x-ray showed he had a "sprain in the shoulder ligaments" and that it was "optimistic" he would be fit for the World Cup.
