The 24-year-old was replaced in Spain's squad for Nations League matches against the Czech Republic and England this week by Jorge de Frutos after suffering the injury last weekend in LaLiga.
"Barrenetxea suffered a severe injury, involving tendon damage... in the hamstring of his right thigh," said La Real in a statement, confirming he will undergo surgery.
Real Sociedad are fifth in LaLiga and also competing in the Europa League, where they sit 20th in the league phase table.
LaLiga
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