For example https://web.wechat.com
By scanning the QR code from my mobile, it automatically logs in with my wechat account.
Here, can QR web sever or QR devices steal the mobile data?
For example https://web.wechat.com
By scanning the QR code from my mobile, it automatically logs in with my wechat account.
Here, can QR web sever or QR devices steal the mobile data?
Short answer: No
Complementing what schroeder said, you can verify the content of that QR code with any QR code scanner (there are some for PCs). I verified and the content is an URL, like:
https://login.weixin.qq.com/l/YYEwfl9Y-A==
By itself those qrcodes are not dangerous for your mobile. However, whatever is in that site is what you need to care of. Some sites may have exploits that could potentially access data in your mobile (specially if your browser/os is not updated or old).
If you check the content of a QRcode and looks like Javascript code, then I would be worried about, however in order that to happen, the QRcode itself would have to have a lot of information in it (making it hard to pack in a "common" size QR code).
So your next question should be: is "wechat.com" safe? If you downloaded their app, you should also ask if that app is safe. That app has much more potential to access your data (depending on what permissions you allowed it), which in that case, if they wanted to steal your data, they don't need the QRcode for that, they already have the app in your phone.