The micro-blogging site has uncovered breaches to privacy, linking data gathered for user security with targeted ads. This comes just months after discovering a similar issue.
Twitter used phone numbers and email addresses provided for security reasons for targeted advertising, the social media platform said Tuesday.
"We recently discovered that when you provided an email address or phone number for safety or security purposes (for example, two-factor authentication) this data may have inadvertently been used for advertising purposes," Twitter said in a statement issued on Tuesday evening.
The statement, released on its website, emphasized that it was an error and that no data had been shared beyond the partnered advertisers, adding that the issue had been resolved as of September 17.
Twitter was unable to state how many people were impacted and the company is not proactively contacting customers directly to inform them of the breach.
A history of targeted advertising
The personal information was used in the company's "tailored audiences and partner audiences advertising system." The system allows companies to target ads at users based on the firms' own marketing lists.
When an advertiser uploaded its marketing list, some users were being matched to those lists based on their security email or phone number.
The company apologized, saying it was "taking steps to make sure we don't make a mistake like this again."
This is not the first time that the micro-blogging platform has discovered similar privacy issues.
In July the company admitted that it had discovered that "certain data"of mobile phone users, such as their country code, may have been shared with advertising partners since May 2018 even if users had not given that permission on their account.
Twitter said it may have shown ads "based on inferences" made about users' devices, without consent.
At the time Twitter stated it was conducting an investigation into why this had happened.
kmm/se (AFP, Reuters)