"It was meant to be stored and shared anonymously, however such poor precautions were taken that deanonymising would not be hard," the report said.
The data sets were controlled by David Stillwell and Michal Kosinski at the University of Cambridge.
"More than 6 million people completed the tests on the myPersonality app and nearly half agreed to share data from their Facebook profiles with the project," said the report.
Alexandr Kogan, at the centre of the British political consultancy firm Cambridge Analytica scandal, was previously part of the project.
"Cambridge Analytica had approached the myPersonality app team in 2013 to get access to the data, but was turned down because of its political ambitions," the report said.
Facebook last month suspended "myPersonality" from its platform, saying the app may have violated its policies.
The social media giant on Monday said that is auditing each and every app that has access to the data of its users and has already suspended 200 apps which failed to comply with its policies.
The company CEO Mark Zuckerberg had promised a thorough investigation and audit into apps that had access to information before Facebook changed its platform policies in 2014 -- significantly reducing the data apps could access.
"To date, thousands of apps have been investigated and around 200 have been suspended -- pending a thorough investigation into whether they did in fact misuse any data," Facebook said.
If Facebook finds evidence that these or other apps did misuse data, it will ban them and notify users via Help Centre on its website.
Appearing before the US Congress in April, Zuckerberg told lawmakers that his own personal data was part of 87 million Facebook users that was improperly shared with Cambridge Analytica.
Business Standard has always strived hard to provide up-to-date information and commentary on developments that are of interest to you and have wider political and economic implications for the country and the world. Your encouragement and constant feedback on how to improve our offering have only made our resolve and commitment to these ideals stronger. Even during these difficult times arising out of Covid-19, we continue to remain committed to keeping you informed and updated with credible news, authoritative views and incisive commentary on topical issues of relevance.
We, however, have a request.
As we battle the economic impact of the pandemic, we need your support even more, so that we can continue to offer you more quality content. Our subscription model has seen an encouraging response from many of you, who have subscribed to our online content. More subscription to our online content can only help us achieve the goals of offering you even better and more relevant content. We believe in free, fair and credible journalism. Your support through more subscriptions can help us practise the journalism to which we are committed.
Support quality journalism and subscribe to Business Standard.