It said it originally thought that the incident was limited to US customers. On September 7 it had said that 143 million Americans as well as 400,000 Brits may have had their names, addresses, and other information stolen in the data breach.
"While our investigation is ongoing and this information may change, at this point, we believe that the incident involves potential access to the personal information of approximately 100,000 Canadian consumers," Equifax said in a statement.
Equifax said it hired a cybersecurity firm to conduct a forensic analysis to determine the scope of the intrusion, including what data was stolen by "criminals who exploited a US website application vulnerability to gain access to certain files."
The company has offered free credit monitoring services to all affected.
Canada's privacy commissioner, meanwhile, has launched an investigation.
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