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Company intelligence
Substack cybersecurity incidents and threat signals
substack.com
This company page brings together public reporting currently associated with Substack. It reflects signals published by Shadow Tier and should not be read as a complete incident history.
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Last 28 days
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Last 90 days
recent published signals
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confidence classifications
June 25, 2026
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Based on all published signals currently linked to Substack. Affected countries come from victim data; the company country above remains a separate profile fact. Counts describe this reporting set, not overall incident prevalence.
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All published signals involving Substack
Substack Discloses Security Incident After Hacker Leaks Data
Substack discovered a security incident on February 3, 2026, where an unauthorized third party accessed limited user data in October 2025. The breach exposed email addresses, phone numbers, and internal metadata for approximately 697,000 users. Substack confirmed that no passwords, credit card numbers, or financial information were compromised. The company has since fixed the vulnerability and is investigating the incident, while warning users to be vigilant against potential phishing attempts.
FAQ
Questions about Substack cybersecurity reporting
What does the Substack page include?
It combines a reviewed organization profile with all current published Shadow Tier signals explicitly linked to Substack.
Does every mention of Substack appear here?
No. A signal must contain a reliable company connection and meet the publication criteria; incidental or ambiguous mentions are excluded.
Why can the incident count change?
The page follows current published reporting. Counts change as new evidence is added, classifications are reviewed, or older signals leave the reporting window.