Yahoo says all 3 billion user accounts were impacted by 2013 security breach for more in go here. https://www.theverge.com/2017/10/3/16414306/yahoo-security-data-breach-3-billion-verizon and here https://techcrunch.com/2017/10/03/yahoo-says-all-3b-accounts-were-impacted-by-2013-breach-not-1b-as-thought/ yahoo FAQ https://help.yahoo.com/kb/account/SLN28451.html?impressions=true