The Poker Tracker website had been compromised and loaded a Magecart script that steals payment information from customers. The compromise was possible because Poker Tracker.com was running Drupal 6.3.3x, an outdated version that has security vulnerabilities. The latest release for the platform is 8.6.17, available since June 17. The owners of PokerTracker.com have been contacted and they acted promptly to fix the problem. The site has improved the Content Security Policy (CSP), a web security standard that allows controlling the resources loaded for specific web pages.
Source: https://www.bleepingcomputer.com/news/security/pokertrackercom-hacked-to-inject-payment-card-stealing-script/