A user of Amazon's smart assistant Alexa was sent 1,700 audio files from a complete stranger, after he requested access to his own recordings.
Amazon described the incident as an "isolated case" and put the mistake down to human error.
The user, based in Germany, said that he informed Amazon of the issue but got no reply.
The files were later deleted from the link Amazon sent him but remained downloaded on his computer.
The online retail giant said in a statement: "This was an unfortunate case of human error and an isolated incident. We have resolved the issue with the two customers involved and have taken steps to further improve our processes. We were also in touch on a precautionary basis with the relevant regulatory authorities."
The man requested access to his data under the new EU General Data Protection Regulation (GDPR).
Steve Kuncewicz, a partner at law firm BLM said that it was "quite embarrassing" for Amazon but the fact that it only involved the data of one person meant the regulator might "take a pragmatic approach".
However the man whose data was exposed could have a civil case to answer should he wish to pursue it, he added.