Certified: The Security+ Prepcast

Zero-day vulnerabilities are software flaws that are unknown to the vendor and, critically, to defenders—giving attackers a window of opportunity to exploit systems with no available patch or signature-based detection. In this episode, we explore what makes zero-days so dangerous, how they are discovered and weaponized, and the typical lifecycle from discovery to disclosure (or exploitation). Zero-days are often used by nation-state actors or advanced persistent threats (APTs) to quietly infiltrate targets, and may be sold on dark web markets for high prices. We examine real-world examples of zero-day attacks and how organizations can implement behavioral analysis, endpoint detection and response (EDR), and network segmentation to detect or limit damage. While zero-days can’t be predicted or patched in advance, you can reduce their impact by preparing for the unknown—through defense-in-depth, threat hunting, and layered detection. In a world where some attackers are always one step ahead, readiness becomes your strongest tool.