Substack won't share official numbers, but it seems like a pretty significant data breach.

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, the hugely popular online content platform with 50 million active subscribers, has confirmed it has been hacked. Here’s what you need to know.

Newsletter platform Substack has confirmed it suffered a security incident, leading to the compromise of users’ email addresses and phone numbers. Chris Best, the CEO of Substack, notified users of ...

The popular blogging platform Substack – used by numerous British comic creators to promote their work – has suffered a data ...

Publishing platform Substack has disclosed a data breach that leaked nearly 700,000 user records after an unauthorized third-party exploited a security flaw.