The bug caused some versions of Firefox to automatically send crash reports to Mozilla’s servers, without users’ authorisation
Mozilla has fixed a bug in its Firefox browser that automatically sent crash data to the company’s servers, whether users had told it to do so or not.
The crash reports contain information about the page that was being viewed in the browser at the time of the crash, and as such could contain private information, Mozilla acknowledged, saying it planned to delete all the inadvertently collected data from its servers.
“While we designed the crash reporting system to be difficult to map back to individuals, we need to be mindful that crash dumps contain the contents of the crashing tab,” Mozilla said in its bug report. “With low frequency they may contain private or identifying information.”
The bug was introduced in version 52 of the browser, released in March, and is fixed in version 57.0.3, released on 28 December.
Data leaks have become a controversial issue, especially where it comes to browsers and also to mobile websites and apps, many of which have been found to send information on users back to developers without users’ knowledge or consent.
In November of last year Google was served with a large-scale lawsuit in the UK over its tracking of Safari users’ browsing activity several years ago.
Many users choose to disable browser crash reporting entirely out of privacy considerations. The reports are used to help developers spot browser bugs.
Given the sensitivity of the issue, Mozilla said it would take steps to ensure no crash reports are automatically submitted unless the user has specifically authorised the browser to do so.
Data deletion headache
Unfortunately, the company said it has no way of distinguishing people who switched on automatic reports from browsers in which the setting was enabled by the software flaw.
As a result, Mozilla said it would disable all automatic reporting for the affected browsers. It is also configuring its servers to discard any new crash reports submitted by the affected software.
Deleting the crash data from the affected browsers may also be difficult, since it is processed and stored in various systems at Mozilla.
“We retain crash reports for up to one year, so the whole data set is potentially impacted,” Mozilla stated.
The company said it planned to delete all the data within the next ten days.
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