Twitter has a major trolling issue and it has for years. CEO Dick Costolo admitted as much in a recent internal memo obtained by The Verge.

The publication said Costolo’s comments came in response to a question on an internal forum regarding a user that is the frequent target of harassment. Specifically, a Twitter employee asks if anything more can be done to remedy the longstanding issue.

In response to the post, Costolo said his company flat out sucks at dealing with abuse and trolls and they’ve sucked at it for years. He added that it’s no secret and the rest of the world talks about it every day, further noting that they lose core user after core user by not addressing the matter.

Costolo goes on to say that he takes full responsibility for not being more aggressive in terms of dealing with it and that he is ashamed and embarrassed.

Moving forward, the executive vowed to start booting trolls off Twitter “right and left” and making sure that when they launch attacks, nobody hears them.

A follow-up message reiterated Costolo’s stance that he takes personal responsibility for the failure and that he is taking full responsibility in making sure that the people working day and night to remedy the situation have the resources they need to handle it.

Twitter declined to comment on the matter but with the company’s fourth quarter earnings report scheduled for later today, we may hear something about it then.