Slack resets tens of thousands of passwords following 2015 data breach
 

Tens of thousands of Slack users will have to change their passwords after the company learned new details about a 2015 data breach. If you created your account before March of that year, haven't changed your password since and don't log in via a sin...

https://www.engadget.com/2019/07/18/...t-data-breach/