Wanna One fans recently brought to notice a particularly troubling issue that has supposedly affected the entire Wanna One fandom. It was alleged that a sasaeng, or an over-obsessive K-pop idol fan, actually runs a fan site within the fandom. Of the two labels under whose banner 'Wanna One' functions as a boy band, YMC Entertainment released a statement where they warned such sasaengs and assured fans that they were doing their best to protect the singers.

As noted by website Soompi, on October 5, the official fan club of Wanna One, called Wannables, began trending the hashtag "#워너원_사생피피_블랙리스트_추가해" on Twitter. Translated into English, it says, "#Blacklist Wanna One Sasaeng PP." The hashtag was a response to an allegation that someone who ran a Wanna One fan site was a sasaeng and the said person even had personal connection with a YMC staff.

The said sasaeng was using this connection to gather inside information about Wanna One as well as finding out ways to get close to the boy band members. Fans even provided a screenshot of a supposed conversation through a messenger, between the sasaeng and a YMC staff.

Addressing this controversy, YMC released a statement on October 6 that read, "We would like to address the current controversy that is being mentioned on social media and community sites. Not only does the involved party in the screenshot of the mobile messenger application have no relation with any of our company employees, but there are no official Wanna one fan staff members with the name shown in the screenshot either. We want it to be known that our company does not personally contact any fans of Wanna One."

They assured Wanna One fans that they were protecting all Wanna One members to the best of their abilities and said, "We have been taking strong action against sasaeng fans and those who do not maintain fan club etiquette. We will continue to do our best to protect our artists in the future." However, they also warned others not to attack YMC staff members and said they would even take legal action against such people.