Substack data breach exposed user email addresses and phone numbers for months before CEO Chris Best confirmed the October ...
Substack said that customer data was accessed in October 2025, but wasn't discovered until early February.
The hacker claims to have stolen nearly 700,000 Substack user records, including email addresses and phone numbers.
Substack confirms a major data breach exposing user emails and phone numbers. What’s behind the breach, and what’s next?