Yahoo and Engadget Exposed in Massive Data Breach Affecting 245 Million Users A recent cybersecurity incident has revealed a significant data exposure involving Yahoo, Engadget, and Yahoo Advertising, impacting an estimated 245 million users under the IAB Europe Transparency and Consent Framework (TCF). The breach stemmed from improper handling of technical identifiers, including browser cookies, device IDs, hashed email addresses, and IP addresses data routinely collected for analytics, targeted advertising, and user authentication. The exposed information, while not directly tied to individual identities in its aggregated form, included precise geolocation data, browsing behavior, and device-specific details (such as OS type and session duration). These identifiers, though anonymized, can be cross-referenced to reconstruct user profiles, posing risks for tracking, phishing, or account takeovers if exploited by malicious actors. The incident highlights vulnerabilities in third-party data-sharing practices, particularly within digital advertising ecosystems. Yahoo’s privacy policies indicate that such data is used to personalize ads, measure engagement, and enhance services, but the exposure underscores the challenges of securing vast repositories of technical identifiers even when compliance frameworks like the TCF are in place. Users were directed to adjust their privacy settings via links to "Privacy & Cookie Settings" or "Privacy Dashboard" on affected platforms, though the breach itself appears to have resulted from systemic data collection rather than a direct cyberattack. The full scope of the exposure and its potential misuse remain under investigation.