Comcast

Comcast Xfininty's login page had a bug that allowed anyone to gain access to the partial Social Security Numbers and partial home addresses of over 26.5 million customers.

The company patched the bug quickly after being notified of its existence.

Source: https://boingboing.net/2018/08/09/most-hated-cable-operator.html

"id": "COM22281122",
"linkid": "comcast",
"type": "Data Leak",
"date": "08/2018",
"severity": "85",
"impact": "4",
"explanation": "Attack with significant impact with customers data leaks"