2013 — Google: A data management firm discovered that Chrome…
Data compromised
Personal information
Technical writeup
A data management firm discovered that Chrome browser users may have had their personal information stored on the hard drives of their computers without their knowledge or consent. Google Chrome regularly stores names, street addresses, email addresses, phone numbers, bank account numbers, credit card numbers, and Social Security numbers in web browsers for later use. It was not known that Chrome's cache also stores the information in plain text.
Root cause
Unintended disclosure