Substack notifies users about a “limited” data breach in October 2025 via a now-patched flaw found on February 3; a threat actor leaked a ~697K-record database
Newsletter platform Substack is notifying users of a data breach after attackers stole their email addresses and phone numbers in October 2025.
BleepingComputer Sergiu Gatlan
Related Coverage
- Notice of Data Breach Rock and Roll Girl · Lori Christian
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- Substack Newsletter Platform Data Breach Saw Phone Numbers, Emails Exposed PCMag · James Peckham
- Substack suffers apparent data breach affecting nearly 700,000 users CyberInsider · Alex Lekander
- Substack Discloses Breach Exposing its User Details After Four-Month Delay The Cyber Express · Mihir Bagwe
- Substack Confirms Data Breach Journey to Success Club · Fabio Posca
- Substack Data Breach Leads to Leak of Nearly 700,000 Records Daily Dark Web
- Substack reports mass data leak: 'This sucks. I'm sorry' Gazetteer SF · Cydney Hayes
- Substack warns customers of data breach following hacker's dark web claims The Record · Jonathan Greig
- Substack confirms data breach affects users' email addresses and phone numbers TechCrunch · Ivan Mehta
- Substack CEO informs users of a data breach Engadget · Matt Tate
- Substack Newsletter Platform Data Breach Saw Phone Numbers, Emails Exposed PCMag · James Peckham
- Substack says intruder lifted emails, phone numbers in months-old breach The Register · Carly Page
- Substack data breach leaks users' email addresses and phone numbers CSO · John E. Dunn
- Hacker claims theft of data from 700,000 Substack users; Company confirms breach Security Affairs · Pierluigi Paganini
- Panera data breach hits over 5 million customers — names, emails, phone numbers and physical addresses exposed Tom's Guide · Scott Younker
- Your email address and phone number may have been leaked online if you use this popular app Neowin · David Uzondu
Discussion
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@shannon_liao
Shannon Liao
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Substack just emailed me saying my email and phone number have been leaked in a data breach [video]