Sony has blocked access to around 93,000 accounts on its PlayStation Network and SOE games service after unauthorised sign-in attempts.
According to a Sony statement, unknown attackers managed to verify members' IDs and passwords, but insisted that no users' credit card details were at risk.
The Japanese consumer electronics giant played down the significance of the breach, saying that "less than one tenth of one percent" of accounts had been affected in the attack, which took place between 7th and 10th October. It went on to suggest that the details may have been stolen from "one or more compromised lists from other companies, sites or sources".
Sony's own servers have had their fair share of security lapses over the last year - the worst of which, when unidentified intruders stole more than 100 million users' personal details, including credit card information, saw the company's PSN gaming network shut down for more than a month.
Sony said it would get in touch with gamers affected by the latest breach via email, instructing them to reset their password. Updates are available on Sony's PlayStation blog.