Substack
Substack
mediumHave I Been Pwned
Disclosed
October 23, 2025
155 days ago
Records
663.1K
Confirmed
Root Cause
Hacking
Industry
Media
Description
In October 2025, the publishing platform Substack suffered a data breach that was subsequently circulated more widely in February 2026. The breach exposed 663k account holder records containing email addresses along with publicly visible profile information from Substack accounts, such as publication names and bios. A subset of records also included phone numbers.
Exposed Data Types
Exposed Data
Email AddressesPhone Numbers