Scheint alles nicht kritisch zu sein. Der "eingedampfte" Teil des Valve-Statements aus News-Bereich des Dampf-Clients:
"...The leak consisted of older text messages that included one-time codes that were only valid for 15-minute time frames and the phone numbers they were sent to. The leaked data did not associate the phone numbers with a Dampf account, password information, payment information or other personal data. Old text messages cannot be used to breach the security of your Dampf account, and whenever a code is used to change your Dampf email or password using SMS, you will receive a confirmation via email and/or Dampf secure messages.
You do not need to change your passwords or phone numbers as a result of this event. It is a good reminder to treat any account security messages that you have not explicitly requested as suspicious. We recommend regularly checking your Steam account security at any time at
https://store.steampowered.com/account/authorizeddevices ..."