The original English sentence was:
“When you receive an upgrade notification on your mobile device, install it immediately. With every upgrade, providers are closing security gaps which can make your device more vulnerable to security breaches.”
It sounds to me as if the upgrades are making the device more vulnerable to security breaches!
A better formulated English for the purpose of internationalization (and common understanding) probably could have read something like this:
“When you receive an upgrade notification on your mobile device, install it immediately. With every upgrade, providers are closing security gaps. Not-closed security gaps make your device vulnerable to security breaches.”
This puts the security breaches in the past. I translated into Danish accordingly, although in Danish we benefit from the fact that we have two different words, “som” and “hvilket”, depending on whether “which” refers to the noun before (“som”) or to the whole sentence before (“hvilket”). In English language that is accomplished by the far more subtle comma before the word “which”: if it’s there, we are referring to the whole preceding sentence, if it’s NOT there, then “which” just refers to the previous word. Who knew? So, in fact, the first quoted English sentence is abolutely correct, as the word “which” (without a comma) refers to the word before it, i.e. “security gaps”. The security gaps are the ones “making your device vulnerable to security breaches”, -and not the “every upgrade” of the previous sentence.
And if you now do know, try to avoid using it that way, because it’s almost guaranteed to get lost in translation.
You can read more about the English rules for “comma before Which” at: http://www.usingenglish.com/forum/ask-teacher/73947-using-comma-before.html