When some users provided Twitter with their phone number to make their account more secure, the company used this information for advertising purposes, the company said today.
This isn’t the first time that a large social network has taken information explicitly meant for the purposes of security, and then quietly or accidentally use it for something else entirely. Facebook did something similar with phone numbers provided by users for two-factor authentication, the company confirmed last year. “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, specifically in our Tailored Audiences and Partner Audiences advertising system,” Twitter’s announcement reads. In short, when an advertiser using Twitter uploaded their own marketing list of email addresses or phone numbers, Twitter may have matched the list to people on Twitter “based on the email or phone number the Twitter account holder provided for safety and security purposes,” the post adds.