The Concentric.com Leak Exposed 1,721 U.S. Email Accounts

HEROIC analysts identified a combolist labeled concentric.com - 1.721 emails, uploaded by a Telegram user on June 10, 2026. The file contains 1,721 records of U.S.-linked email addresses paired with plaintext passwords and the URLs those credentials access. Why this is dangerous: this list was built specifically around accounts tied to concentric.com, giving an attacker a focused set of U.S. users to target rather than a random mix of addresses from around the world. A narrower, verified list like this is often more valuable to attackers because it increases the odds that the accounts are active and still in use. What was exposed: email addresses, plaintext passwords, and the URLs linked to each account. Why this matters: when a breach concentrates on accounts from one country or platform, it becomes easier for attackers to build convincing, localized phishing attempts or run credential stuffing campaigns against U.S. financial and shopping sites where those same passwords may be reused. That combination raises the risk of account takeover, identity theft, and financial fraud for everyone on the list. How combolists work: a combolist is a compiled set of email and password pairs, often gathered from stealer logs, older breaches, or scraped account data, then filtered down to a specific domain, country, or user base before being shared. Filtering to U.S. accounts tied to one domain, as seen here, makes the list easier for attackers to target with region-specific scams. Check if you are affected: HEROIC's free breach scanner checks your email against a database of more than 400 billion leaked records, including combolists like this one. Run a scan to see if your email was part of this exposure and learn which passwords to change.