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Twitter Tells Users Firefox Possibly Exposed Personal Information

Twitter informed users on Thursday that their personal information may have been exposed due to the way the Firefox web browser stores cached data.

The social media giant discovered recently that Firefox’s cache stored some private information associated with the use of Twitter, including sent or received direct messages and the downloaded data archive. However, this would only be problematic on shared computers.

“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,” Twitter explained. “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 company added in a message posted on Twitter, “There isn’t a standard for how browsers cache downloaded data. We noticed that the way Firefox stores cached Twitter data is different (but not wrong) than other browsers and could put your non-public info at risk.”

Firefox only stores cached data for 7 days, which means the Twitter data would have only been exposed for a limited period of time. Users can also manually clear the cache, which Twitter recommends for users who accessed Twitter from a shared or public device.

Twitter has made some changes on its end to ensure Firefox no longer stores potentially sensitive information belonging to its users. Safari and Chrome do not appear to be impacted.

Twitter has disclosed several security and privacy issues over the past few years, including related to the use of account security information for advertising, the Android app exposing protected tweets, an API vulnerability exploited to match usernames to phone numbers, the Android app allowing hackers to obtain sensitive data and hijack accounts, and direct messages being exposed to third-party developers.

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Related: Twitter Users Can Now Use 2FA Without a Phone Number

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.