Details of 34,000 Steam users have been exposed during a DDoS attack on the Steam gaming platform. Valve company that owns the Steam platform confirmed the serious security issue caused by an internal error. The company in response to the attack deployed caching rules designed to mitigate the threat and minimize the impact on the platform. Steam users who did not access their account details page or checkout page between 11:50 PST and 13:20 PST on December 25 are not affected. The content of these requests varied by page, but some pages included a Steam users billing address, the last four digits of their Steam Guard phone number, their purchase history, and/or their email address.”]
Source: https://securityaffairs.co/wordpress/43189/security/steam-users-data-exposed.html