The social security numbers (CPR-number) of over 900,000 Danes were inadvertently released online by the economy and interior ministry on Wednesday, financial daily Børsen has reported.
The social security numbers of all Danes on the so-called Robinson List, a list of individuals who have opted out of receiving advertisements in the post, were released due to an error within the ministry.
Carsten Grage, an official with the national CPR registry, confirmed to Børsen that “there has been an incident”.
According to Grage, a quarterly data file that normally only contains individuals’ names and addresses, this time also included their CPR numbers.
The numbers, which are used for almost all interactions with the public sector, were available online for nearly an hour before the error was discovered. According to Børsen, at least 18 companies downloaded the CPR numbers for marketing purposes and have been given until today at 4pm to confirm that they have deleted the sensitive information.
Denmark’s social security number system has recently come under fire from critics who claim the system is too vulnerable to hacking and ID theft. CPR numbers include a resident’s birthdate as the first six digits, followed by four unique numbers. Males are assigned a CPR number that ends in an odd digit, while females have a CPR number ending in an even digit.
Two weeks ago, a 'hacktivist' released the CPR numbers of over 90 MPs in a protest against Denmark's surveillance laws.