Thousands of apps running code built by Chinese Internet giant Baidu have collected and transmitted users' personal information to the company, much of it easily intercepted, researchers say.
The apps have been downloaded hundreds of millions of times.
The researchers at Canada-based Citizen Lab said they found the problems in an Android software development kit developed by Baidu. These affected Baidu's mobile browser and apps developed by Baidu and other firms using the same kit.
Baidu's Windows browser was also affected, they said.