In yet another breach of user privacy by a large social media network, Twitter admitted on Tuesday that a number of users’ emails and phone numbers may have been misused by the company and “inadvertently” used for ad purposes.

The issue, according to a blogpost by Twitter, cropped up because the company’s algorithms “may have” accidentally matched people’s emails and phone numbers with contact lists uploaded by advertisers to match their own customers with Twitter users. The company said that it “may have matched people on Twitter [to marketers’ lists] based on the email or phone number the Twitter account holder provided for safety and security purposes.”

Twitter is claiming that while they aren’t certain of the number of users affected by this accident, the company is making this announcement in an effort to be transparent with its users. The company also reaffirmed that “no personal data was ever shared externally with our partners or any other third parties.”

This is just the latest in a series of privacy and security issues that Twitter has had to face in the last year. Earlier in August, the company’s CEO Jack Dorsey’s account was hacked. Before that, the company told users that it had accidentally collected and shared users’ location data with a third party, among other issues that have been plaguing the company as far as security and privacy is concerned.

In light of this latest issue, the company might have to face an investigation by the FTC, along with a possible fine being imposed on it, especially since Facebook just recently got a slap on the wrist from the FTC for a similar issue. Ashkan Soltani, a former chief technologies at the FTC said, “Given that Facebook got dinged for this exact practice, I think it likely meets the threshold of material omission or even deception under Section 5 on its own. That’s further compounded by the fact that Twitter is also under order already by the FTC.”