If You Reuse Passwords, the MixDomain Combolist Should Concern You

HEROIC analysts reviewed a combolist file named MixDomain Size 4M that a Telegram user uploaded on March 21, 2025. Despite the "4M" in the file name suggesting millions of records, HEROIC's verification confirms the actual count at 55,171 records, each pairing an email address with a plaintext password and the URL that credential works on. Worth noting upfront: the file name overstates the real scale, but 55,171 exposed logins is still a significant exposure. Why This Is Dangerous: Every record in this file is a working login handed to an attacker with no effort required. The email, its plaintext password, and the exact website it opens are all sitting together in one line. What Was Exposed: - Email addresses - Plaintext passwords - URLs tied to each credential pair Why This Matters: With 55,171 credential pairs in circulation, the real danger is credential stuffing, where attackers automatically test each email and password against banking sites, email providers, and social platforms. If you have reused a password anywhere, this file is exactly the kind of leak that can turn into account takeover, identity theft, or financial fraud. How This Combolist Was Built: A combolist compiles stolen or leaked login pairs from a mix of sources, older breaches, phishing hauls, or malware logs, then groups them by the site each credential unlocks. That mixed origin is likely why this one is labeled "MixDomain." These files are cheap to trade on Telegram and easy to run through automated login-testing tools. Check If You Are Affected: HEROIC's free breach scanner checks your email against more than 400 billion exposed records, including this MixDomain leak. Run a free scan now to see if your credentials are part of it.