If you used Firefox to access Twitter, your non-public info may have been exposed
Mozilla Firefox is damn good web browser that is largely open source and focuses on privacy and security. That is why I choose it as my default browser on both Windows 10 and Linux-based operating systems such as Ubuntu and Fedora. Many people wisely choose Firefox for the same reasons.
Sadly, today, we discover that if you have been using Mozilla Firefox to access Twitter, you may have had non-public information data saved locally to cache. Twitter makes it clear that other major browsers, such as Google Chrome and Apple Safari, are not affected. Thankfully, the social network says it fixed the issue on its end.
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Why did this happen? Twitter tells BetaNews, "This is an issue related to the HTTP Header default browser setting on Mozilla but not other browsers. Twitter implemented a change so that Mozilla Firefox no longer stores Twitter data in its cache, but it was neither an error nor a leak on Mozilla's behalf." In other words, there is no reason to fault Firefox here, folks.
"We recently learned that the way Mozilla Firefox stores cached data may have resulted in non-public information being inadvertently stored in the browser's cache. This means that if you accessed Twitter from a shared or public computer via Mozilla Firefox and took actions like downloading your Twitter data archive or sending or receiving media via Direct Message, this information may have been stored in the browser’s cache even after you logged out of Twitter. The Mozilla Firefox browser’s cache retention period is set to 7 days and after that time the information should have automatically been removed from the cache. This issue did not impact people using other browsers like Safari or Chrome," says Twitter
The social network further says, "We have implemented a change on our end so that going forward the Firefox browser cache will no longer store your personal information. If you use, or have used, a public or shared computer to access Twitter, we encourage you to clear the browser cache before logging out, and to be cautious about the personal information you download on a computer that other people use."
We’re looking into this Twitter bug right now, but rest assured: when you use Firefox, your cached data stays on your device. So IF the data stayed in your cache, it would only have been viewable on that device!
— Firefox 🔥 (@firefox) April 2, 2020
Twitter has been proactively alerting Firefox users to this situation via a pop-up when using the service. Yours truly got the pop-up warning while using the iOS app -- I assume Twitter flagged me as an impacted Firefox user based on my desktop usage. You can see the pop-up alert above -- which I Tweeted to the official Firefox Twitter account -- followed by a prompt response from @Firefox.
If you are someone that accesses Twitter through Firefox on your own computer, I wouldn't be too concerned. Odds are, you probably didn't have any important information leaked to your cache. Even if you did, as long as your device is secure, all should be OK.
I mean, look, could a hacker have accessed your machine and stolen that non-public data by specifically searching it out in the cache? It is possible, yes, but not likely. You should really only be worried if you used a public computer to access Twitter, which is a risky practice on its own.