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Breach occurred 2025-04-11VerifiedWhat happened
During 2025, the threat-intelligence firm Synthient aggregated 2 billion unique email addresses disclosed in credential-stuffing lists found across multiple malicious internet sources. Comprised of email addresses and passwords from previous data breaches, these lists are used by attackers to compromise other, unrelated accounts of victims who have reused their passwords. The data also included 1.3 billion unique passwords, which are now searchable in Pwned Passwords. Working to turn breached data into awareness, Synthient partnered with HIBP to help victims of cybercrime understand their exposure.
Data exposed
Frequently asked questions
The Synthient Credential Stuffing Threat Data data breach occurred on April 11, 2025. It was added to Have I Been Pwned's breach catalog on November 6, 2025.
1,957,476,021 accounts were affected by the Synthient Credential Stuffing Threat Data data breach, according to Have I Been Pwned's records.
The Synthient Credential Stuffing Threat Data breach exposed the following data types: Email addresses, Passwords.
Yes. Have I Been Pwned has verified the Synthient Credential Stuffing Threat Data breach, meaning there's confirmed evidence the exposed data is genuine and tied to real accounts.
Use KazaSec's free Email Breach Checker (/tools/breach-check) to check whether a specific email address has surfaced in the Synthient Credential Stuffing Threat Data breach, or any other known breach — the tool never stores what you search.
Our free Email Breach Checker tells you whether a specific email address has surfaced in this breach — or any other known breach — without ever storing what you search.
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