verified2025-10-23
SubstackSubstack breach
substack.com · 663,121 records compromised
Records
663K
Breach date
2025-10-23
Domain
substack.com
Data classes
2
Description
In October 2025, the publishing platform Substack suffered a data breach that was subsequently circulated more widely in February 2026. The breach exposed 663k account holder records containing email addresses along with publicly visible profile information from Substack accounts, such as publication names and bios. A subset of records also included phone numbers.
Compromised data classes· 2
Email addressesPhone numbers
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.