Prisoners have asked to be isolated for days on end and transferred to different facilities after access to news websites sparked violence
NSW inmates gained access in August to content from The Daily Telegraph and the BBC, as well as the Australian Electoral Commission.
But the search function on each website was not properly deactivated, turning 11,000 prison-issued tablets into discovery tools for fellow inmates' reported criminal histories.
The stuff-up, revealed through questioning by Greens MP Sue Higginson in parliament, had resulted in violence and prisoners requesting protection, Corrective Services NSW said.
"The state has a duty of care to inmates which includes keeping them safe," Ms Higginson said on Thursday.
"Some inmates have apparently spent 18 days straight in their cells because they believe it is too dangerous for them to come out."
Corrective Services NSW Commissioner Kevin Corcoran said access to the news and electoral sites was cut after two weeks and would not be reactivated until officials were "100 per cent certain" the search function could not be used again.
He was not immediately clear on why the electoral commission was one of the sites blocked.
"It's really unfortunate that harm has occurred, but we have very robust systems in place to look after people who are at risk," Mr Corcoran told a budget estimates hearing on Wednesday.
Inmates can still access the ABC News website.
Ms Higginson said a person inside Junee prison had warned that someone might get killed unless something was done.
"I understand that the Daily Telegraph news source was likely provided as a well-intended initiative, but it was a massive oversight not to test the search function of the news site which has led to this awful situation," she said.
