More than 25 percent of used vehicles sold at eight CarMax locations across the U.S. contained safety defects that weren’t repaired, despite being under recall, according to a review by car safety advocates. Some of the cars included unrepaired Takata airbags, which have been linked to numerous deaths.

Problems with used cars with open recalls being sold aren’t new. But the study—conducted by the Center For Auto Safety, the Consumers for Auto Reliability and Safety Foundation and the MASSPIRG Education Fund—found sales of vehicles with unfixed safety recalls have doubled, compared to a previous sutdy in 2015 that looked at five CarMax locations.