Substack, the hugely popular online content platform with 50 million active subscribers, has confirmed it has been hacked.

Substack said that customer data was accessed in October 2025, but wasn't discovered until early February.

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

The hacker claims to have stolen nearly 700,000 Substack user records, including email addresses and phone numbers.

Substack states that the security flaw has now been fixed and that a full investigation is underway. There are currently no ...

The company has emailed affected users after a dark web source claims the data of almost 700,000 users was compromised.

The digital publishing platform Substack has told some of its users that their data was stolen in a security breach. The ...

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 ...

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Substack has confirmed a major data breach that exposed emails and phone numbers for approximately 700,000 users, with the ...