Substack data breach exposed users’ emails and phone numbers
ThinkingNews Desk · how this was written
Substack experienced a security incident in October 2025 in which a threat actor accessed internal data and extracted a database of roughly 697,000 user records. The compromised information includes email addresses and phone numbers, while passwords and financial details remain secure; the breach was discovered in early February and has since been patched.
Written from all 4 reports below, not from any single one.
How it was reported
- The Verge·Substack data breach exposed users’ emails and phone numbers
Substack experienced a security incident where email addresses and phone numbers were exposed. A hacker accessed internal data without authorization in October 2025. Passwords and financial information remain secure.
- TechMeme·Substack notifies users about a "limited" data breach in October 2025, found on February 3 and now patched; a threat actor leaked a database of ~697K records (Sergiu Gatlan/BleepingComputer)
Substack notified users of a data breach in October 2025. Attackers stole email addresses and phone numbers. A database of ~697K records was leaked.
- TechCrunch·Substack confirms data breach affects users’ email addresses and phone numbers
Substack confirmed a data breach affecting users' email addresses and phone numbers. The breach occurred in October 2025 but was only discovered in early February. Customer data was accessed during this time.
- Engadget·Substack CEO informs users of a data breach
A data breach was announced, likely exposing user information, though details of the breach are not available.
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