The incident happened at around 1.10am on Thursday in Burns Court, Kirkintilloch, East Dunbartonshire. Two men carrying a weapon forced their way into the flat, threatened a 64-year-old woman and attacked her 45-year-old son, leaving him with deep cuts on his head.
He was taken to Glasgow Royal Infirmary for treatment and later released. His mother was not injured but left badly shaken by the attack, police said. There does not appear to be any motive for the attack, according to officers.
The first suspect is around 6ft 2in, aged around 30 with a heavy build. The only description of the second suspect is he was younger than the first suspect and had a "podgy" build. Police carried out door-to-door inquiries in the area and are appealing for witnesses.
Detective Inspector Douglas Robertson said: "There doesn't appear to be a motive for this attack."