Firefox users who use Twitter may get a notification by the service when they connect to the site the next time that informs them that personal data may have been stored inadvertently in the browser's cache.
The message states:
Important information for Firefox users
We recently learned that the way Mozilla Firefox stores cached data from Twitter may have resulted in non-public information being inadvertently stored in the browser's cache. For example, if you downloaded your data using Firefox, the browser may have retained a copy of the download for a period of time. We have made changes to prevent this from happening again.
According to Twitter's notification, personal information such as downloaded data from Twitter or direct message, could have been cached by Firefox. While that is not a problem on a device with a single-user, information could have leaked on devices that are used by multiple users, e.g. on public Internet workstations.
Update: Mozilla published a technical analysis of the issue here.
Other users or administrators could find the data if they browsed the cache of the browser. Firefox's default caching period is set to 7 days but it is possible to change the retention in the browser's settings.
Twitter notes that it has made changes so that the data is no longer stored in Firefox's cache. Other browsers, non-Firefox-based browsers, are not affected by the issue according to Twitter. Other Firefox-based browsers may be affected by the issue on the other hand.
It is unclear if Firefox's caching may cause the same issue on other services. Betanews colleague Brian Faglioli asked Mozilla about this on Twitter and received a reply stating that the organization was looking into this.
It is a good practice to clear caches and other data after using public machines to access content on the Internet or work locally on a device. Some public workstations are configured to erase caches automatically when users sign-out. Firefox users may use the shortcut Ctrl-Shift-Del to clear the history of the browser.Advertisement
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