A merchant vessel was "taking on water" off the Yemeni port of Hodeida on Tuesday after it was damaged in a missile attack, maritime security firm Ambrey said.
The ship was "targeted with three missiles," Ambrey said, adding that a distress call said it "had sustained damage to the cargo hold and was taking on water".
The firm did not identify the ship or say how many crew members were on board.
There was no immediate claim of responsibility for the attack, which came amid a campaign of drone and missile attacks by Yemen's Iran-backed Houthi rebels.
The rebels' attacks, which they say are in support of the Palestinians, have prompted some shipping companies to detour around southern Africa to avoid the Red Sea, a vital route that normally carries about 12 percent of global trade, according to the International Chamber of Shipping.
Since January, the United States and Britain have launched retaliatory strikes on Houthi targets in Yemen in response to the attacks on shipping.
The strikes have done little to deter the Houthis, who have vowed to target US and British vessels as well as all ships heading to Israeli ports.