Twitter has apologised for inadvertently sharing people's phone numbers and email addresses with advertisers, just two months after it made a similar mistake.
The social network said in a statement that is has "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".
The fault applied specifically to Twitter's tailored audiences and partner audiences ad system. The former allows advertisers to target ads to consumers based on their own marketing lists, while the latter allows advertisers to use the same targeting features with consumer data garnered via third parties.
"When an advertiser uploaded their marketing list, we may have matched people on Twitter to their list based on the email or phone number the Twitter account holder provided for safety and security purposes. This was an error and we apologise."
While Twitter said it does not know how many people were hit by the data leak, it added that as of 17 September it had addressed the issue and is "no longer using phone numbers or email addresses collected for safety or security purposes for advertising".
On 8 August, Twitter apologised after revealing more bugs on its platform that meant data was shared with advertisers without permission.
The latest apology said: "We’re very sorry this happened and are taking steps to make sure we don’t make a mistake like this again."