It's believed tens of thousands of Australians and New Zealanders may have been caught up in a leak of confidential information by children's technology giant VTech.
The Hong Kong-based company, which manufactures gadgets, tablets and baby monitors, has acknowledged a breach after the details of up to five million VTech customers worldwide were accessed by hackers in mid-November.
The information includes names, addresses, passwords and the names and birthdays of up to 200,000 children.
Hackers are also able to link children with their parents and access their photographs and voicelogs.
"We are aware of reports of some 18,000 Australian parents and children being affected by the VTech app breach," Australian consumer advocacy group Choice said in a statement.
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"The breach is a timely reminder to change your passwords on a regular basis and check to see what data security measures you have in place in your home."
Australian digital security expert Troy Hunt, who helped Motherboard website verify the leak, said companies weren't getting the message on securing customer data.
"Taking security seriously is something you need to do before a data breach, not something you say afterwards to placate people," Mr Hunt wrote on his blog.
Children's eSafety Commissioner Alastair MacGibbon said the theft of data relating to children added "a degree of injustice" to the breach.
"Why are we collecting this information to start with? If you don't collect it, you can't lose it," Mr MacGibbon said.
The hacker, reportedly speaking with Motherboard, said he had no plans to use the data.
"Frankly, it makes me sick that I was able to get all this stuff," the hacker said.
