Researchers say a flaw in some Chrysler vehicles allows hackers to control the cars remotely using the internet.
Hackers can disable brakes, shut down the engine, make electronics go haywire, and even drive the cars off the road.
The problems stem from a flaw in the wireless service "U-Connect" that hooks the vehicles to the Sprint Network.
Researchers Charlie Miller and Chris Valasek demonstrated the hack to Wired Magazine on Tuesday. They hijacked a Jeep Cherokee remotely.
Miller and Valasek said Jeep Cherokees, Chrysler 200s, Dodge Rams, and several other models made since late 2013 are vulnerable to cyber-attacks.
Chrysler officials said it is now offering a software upgrade to fix the problem, and that customers should install it as soon as possible. The update includes U-Connect improvements introduced in the 2015 model year.
"Similar to a smartphone or tablet, vehicle software can require updates for improved security protection to reduce the potential risk of unauthorized and unlawful access to vehicle systems. Today’s software security update, provided at no cost to customers, also includes Uconnect improvements introduced in the 2015 model year designed to enhance customer convenience and enjoyment of their vehicle," according to a Chrysler statement.