According to the New York Times, Twitter managers only recently found out about the serious leak. That would mean that the software code could have been online at Github for a good two months. The damage is not yet foreseeable.
(dpa) Portions of Twitter’s software code have been exposed on the internet as a result of an unusually serious data breach. The short message service is now demanding information about who or those allegedly responsible behind the publication, as evidenced by court documents from the weekend. Twitter also requested data from the programming platform Github on all users who might have seen or downloaded the computer code there.