The show, which aired in 2010, included user names, email addresses, location, postcodes and encrypted passwords of almost 50,000 users.
“Overnight the ABC was made aware that an ABC television program website was hacked,” the corporation said via a statement.
“At this stage, we are still investigating the details of the breach.
“However, we do know that it has exposed the name, user name and a hashed version of the password that audience members used to register on the program website.
“As soon as the ABC was made aware of this activity the site was shut down.”
A Twitter user going by the name Phr0zenMyst said the attack was in response to the ABC’s decision to “[give] a platform for (right-wing Dutch politician) Geert Wilders to spread hatred,” following an interview on Lateline.
“This breach originated at an overseas location and an activist has claimed responsibility for it,” said the ABC.
“The ABC will be in contact with audience members who have been directly affected.”
ABC is currently screening a follow-up series, Making Couples Happy.