Last.fm has urged users to change their account passwords as a precaution following "the leak of some Last.fm user passwords."
The music streaming website said the warning "follows recent password leaks on other sites, as well as information posted online."
Last.fm did not disclose how many accounts are at risk, or any details pertaining to its security.
This follows in the footsteps of 'professional' social network LinkedIn and dating website eHarmony which both suffered security breaches earlier this week. At this early stage, it would be premature to suggest the three breaches are connected.
Sophos' Graham Cluley told the BBC he is concerned that the sites have shared a similar flaw in security.
"Can it be coincidence? It seems unlikely to me. There's a mystery in the middle of the LinkedIn breach about how they got the data. You have to worry there's a common vulnerability," he said. "The fact is, the only people who know are the hackers and maybe the companies concerned, but they may be struggling to work out what's happened."
London-based Last.fm was bought by CBS in 2007 for £140 million ($280m). ZDNet and CNET are also owned by CBS.
Last.fm was not immediately available for comment.
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