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Name one example of that, which has happened without user authorisation.
Jailbreaking is hacking, a malicious third party can exploit the same holes that jailbreaks use. They are, like it or not, major security holes in iOS that allow you to bypass many of the systems protections. Those quick and easy jailbreak by visiting a website can easily be a malware install.

Name one example of that, which has happened without user authorisation.

I found this the other day:

http://9to5mac.com/2016/07/30/pangu-jailbreak-potential-hack/
 
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