Synthient Credential Stuffing Threat Data data breach

What 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.

What data leaked

• Email addresses
• Passwords

What to do if you had an account

1. Change the password. Change your password on this service. If you used the same password anywhere else, change it there too: attackers try leaked email and password pairs on other sites automatically. A password manager makes one unique password per site practical.
2. Turn on two-step sign-in. Enable two-factor authentication where the service offers it, preferably with an authenticator app or a passkey. A leaked password alone is then not enough to get in.
3. Expect targeted phishing. Leaked contact details are used to write convincing fake messages that mention the breached company or your real name. Do not click links in unexpected emails or texts about this account; go to the site by typing its address.

Check your email at haveibeenpwned.com

We do not run email lookups ourselves. The search is done on haveibeenpwned.com, the service this list comes from.