Synthient Credential Stuffing Dataset - 2B Emails in Have I Been Pwned

Synthient credential stuffing threat data adds a massive aggregated dataset of reused credentials to Have I Been Pwned’s breach corpus. Synthient credential stuffing threat data was compiled in 2025 by a threat-intelligence firm that collected two billion unique email addresses and 1.3 billion unique passwords from credential-stuffing lists circulating on criminal forums and paste sites. These records do not represent a single breach but rather a consolidation of leaked credentials from numerous prior incidents, repackaged for attackers seeking scalable account takeover. Synthient credential stuffing threat data is particularly dangerous because adversaries use these lists to test known email and password combinations against unrelated services, exploiting users’ tendency to reuse passwords. The inclusion of the password corpus in Have I Been Pwned’s Pwned Passwords service allows organizations and individuals to check whether their credentials appear in the dataset and to enforce policies preventing the use of compromised passwords. Nonetheless, the sheer volume of exposed combinations underscores that many organizations still rely on password-only authentication and weak rotation practices. For security leaders, Synthient credential stuffing threat data demonstrates that credential reuse remains a systemic risk that cannot be fully mitigated through password hygiene campaigns alone. Multi-factor authentication, conditional access, and detection of unusual login patterns must work together to blunt the impact of these aggregated attack datasets.