All Breaches
October 23, 2025 Verified Publishing

Substack Data Breach

The Substack data breach was recorded with account registrations affecting the publishing platform in October 2025 and circulating more widely in February 2026.

663.1 Thousand
Reported Records
2
Data Types
High
Severity
Yes
Verification

Exposed Data Types

2
Email addresses
Phone numbers

Additional Information

Added DateFebruary 6, 2026
Breach DateOctober 23, 2025
Domainsubstack.com
SourceThird-party breach
Last Content UpdateJuly 19, 2026

Verification and editorial method

LeakData compares the incident name, date, affected-record count, and exposed data types with accessible sources. Unverified fields are not presented as facts, and records are updated when new evidence becomes available.

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Company Information

Company NameSubstack
SectorPublishing
CountryUnited States
Websitesubstack.com

Risk Level

High

The reported impact exceeds 100 thousand and falls within the high severity band.

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