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Substack says intruder lifted emails, phone numbers
Substack disclosed that about 700,000 user email addresses and phone numbers were exposed in a breach detected four months after the October 2025 attack.
- On February 3, 2026, Substack said it discovered evidence of a system compromise and emailed affected users this week, with CEO Chris Best confirming the breach exposed emails, phone numbers, and metadata in October 2025.
- Substack says an unauthorized third party exploited a flaw in October, with detection delayed for four months; it has since patched the flaw and launched an internal investigation.
- A dataset of 697,313 alleged records surfaced on BreachForums, with BleepingComputer and other security outlets reporting it includes names, emails, and phone numbers, though Substack has not tied it definitively to its October breach.
- Substack says it has found no evidence of misuse but warns users to watch for phishing and says affected account holders will be contacted directly by Substack via email.
- Substack's scale—more than 50 million active subscriptions—raises stakes for exposed data, following its July 2020 accidental email exposure, while key questions about scope and detection remain.
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21 Articles
21 Articles
Substack data breach exposed users’ emails and phone numbers
Substack is notifying some users that the email addresses and phone numbers linked to their accounts were exposed in a "security incident" last year. In an email to account holders, Substack CEO Chris Best said that a hacker had accessed internal data without authorization in October 2025, but that passwords, credit card numbers, and other financial information remain secure. "On February 3rd, we identified evidence of a problem with our systems…
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Total News Sources21
Leaning Left3Leaning Right0Center4Last UpdatedBias Distribution57% Center
Bias Distribution
- 57% of the sources are Center
57% Center
L 43%
C 57%
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