Dozens of lawsuits allege Kia and Hyundai failed to include a common security feature in their vehicles, leading to a surge of car thefts aided by viral videos on TikTok and YouTube demonstrating exactly how to steal them.

Car owners have filed more than 30 class actions, alleging Kia America Inc. and Hyundai Motor America failed to install an “immobilizer”—a security flaw exploited by a group of Milwaukee teenagers calling themselves Kia Boyz, whose tutorials on social media have spawned a rise in thefts of the vehicles.