What Is a Data Leak? Complete Guide to Causes, Risks & How to Check Yours
Brief
A data leak happens when sensitive information is exposed to unauthorized parties, usually by accident, rather than through a targeted cyberattack. It can be as simple as a misconfigured database left open online or as damaging as an entire customer list uploaded to the wrong server no hacker required, just a mistake with real consequences.
The scale of that risk is only growing. According to IBM’s 2026 Cost of a Data Breach Report, the average breach now costs organizations $4. 99 million, a record high driven largely by AI-assisted attacks and slower detection times.
For individuals, the fallout looks different but is just as real: leaked emails, passwords, and personal records feed directly into phishing campaigns, account takeovers, and identity theft.