**EXPERTS DISCOVER MASSIVE DATABASE EXPOSING 4.3 BILLION PROFESSIONAL RECORDS**

A staggering 16TB MongoDB database containing over 4.3 billion professional records was left unsecured, allowing malicious actors to potentially access sensitive information. The database, which was discovered on November 23, 2025, by researchers Bob Diachenko and nexos.ai, remained exposed for two days before being secured.

**A GOLDMINE FOR CYBERCRIMINALS**

The database, which was found to be accessible via a publicly exposed MongoDB instance, contained nine collections, each holding vast amounts of data. The "unique_profiles" dataset alone listed over 732 million records with image URLs, while the "people" collection added enrichment metrics and Apollo IDs linked to the Apollo.io ecosystem.

**EXPOSED RECORDS INCLUDE PERSONAL DETAILS AND LINKEDIN DATA**

Researchers analyzed the unsecured database and found that at least three collections exposed nearly two billion personal records. These included:

* Names * Emails * Phone numbers * LinkedIn links * Job roles * Employers * Work history * Education * Locations * Skills * Languages * Social accounts

**DATA COULD DATE BACK YEARS**

While the timestamps on the data suggest that it was collected or updated in 2025, researchers warned that some of the information may date back years. This is due to possible scrapes from large LinkedIn leaks claimed by threat actors in 2021.

**OWNERSHIP OF THE LEAKED DATASET REMAINS UNCLEAR**

Despite finding clues suggesting a lead-generation company as the owner of the dataset, researchers stopped short of attribution. The firm claims access to over 700 million professionals, closely matching the exposed "unique_profiles" count, and the database went offline a day after notification.

**A PERFECT STORM FOR CYBERCRIMINALS**

The leak is particularly concerning due to its sheer scale and structure. With billions of records, malicious actors can automate personalized scams, reduce prep time, and focus on high-value targets, including Fortune 500 employees. Large language models (LLMs) can generate personalized messages based on user profile information, making it easy for attackers to craft convincing phishing emails.

**A PRIME TARGET FOR MALICIOUS ACTORS**

Large datasets like this one are a prime target for malicious actors, as they act as a strong foundational base for profile enrichment based on other data leaks. This enables attackers to craft a large, searchable database of personal data that can be enriched with additional information, such as passwords and device identifiers.

**SECURITY IMPACT IS SEVERE**

The consequences of this leak are severe, enabling malicious actors to simplify social engineering and credential stuffing attacks. With billions of records at their disposal, attackers can automate personalized scams, making it increasingly difficult for organizations to protect themselves against these types of threats.

**STAY VIGILANT AND PROTECT YOURSELF**

As the cybersecurity landscape continues to evolve, it's essential to stay vigilant and take proactive measures to protect yourself and your organization from these types of attacks. Stay informed about the latest threats and trends in the industry by following our Twitter handle @securityaffairs and Facebook page.

**READ MORE ABOUT THE LEAK AND ITS IMPACT ON CYBERSECURITY**

To learn more about this leak and its impact on cybersecurity, read our follow-up article and stay tuned for updates on this developing story.