The leak apparently had seventh season's fifth episode plot details alongside "castings, script summaries and marketing materials" for the popular fantasy drama, according to The Hollywood Reporter.
The material came Monday in an email message to the international publication that also contained nine files with labels-- "Confidential" and "Script GOT7."
"HBO believed that further leaks might emerge from this cyber incident when we confirmed it last week. As we said, the forensic review is ongoing," a representative of HBO said.
"While it has been reported that a number of emails have been made public, the review to date has not given us a reason to believe that our e-mail system as a whole has been compromised. We continue to work around the clock with outside cybersecurity firms and law enforcement to resolve the incident."
The network has acknowledged the hack, but has not yet given out any details about the types of files hackers were able to obtain.
The fourth episode of "Game of Thrones" season seven had also landed online ahead of its August 6th premiere.
However, according to a spokesperson from HBO, the leak was related to one of HBO's distribution partners, Star India, and had no relation to the hack.