Twitter is informing users that tweets posted to their Circle, which should have only been seen by specified individuals, may have also been visible to others.

Launched in August 2022, Twitter Circle allows users to share their thoughts with a smaller group — up to 150 selected users. 

In April, users started noticing that tweets that were meant to be shared only with members of their Circle were actually visible to other people, including people who were not even following them.

Twitter recently started sending out emails to affected Circle users, confirming the data exposure, which it has described as a ‘security incident’.

“In April 2023, a security incident may have allowed users outside of your Twitter Circle to see tweets that should have otherwise been limited to the Circle to which you were posting,” Twitter said in these emails. “The issue was identified by our security team and immediately fixed so that these tweets were no longer visible outside of your Circle.”

Twitter said it conducted a thorough investigation into the cause of the issue, but did not share any technical details. 

Twitter data security issues are not uncommon. For instance, a vulnerability patched in early 2022 had been exploited to collect data on millions of Twitter users. 

However, not every incident involving Twitter user data circulating on the dark web is related to the exploitation of a vulnerability. Earlier this year, the social media giant told users that a couple of databases containing 200 million and 400 million records were not created as a result of a vulnerability being exploited, confirming third-party reports that they were likely obtained through web scraping. 

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Related: Twitter Ex-Security Chief Tells US Congress of Security Concerns

https://www.securityweek.com/private-tweets-exposed-due-to-twitter-circle-security-bug/