A zero-day exploit is an attack that uses a previously unknown software flaw—called a zero-day vulnerability—before the developer knows about it or has released a fix. Hackers use zero-day exploits to steal data, gain system access, install malware, or disrupt operations, often with no warning. These attacks are typically used in targeted intrusions, cyber-espionage, or high-value attacks, and are hard to detect because traditional security tools don’t recognize them yet.
Zero-day exploits are often used in targeted attacks and are difficult to block because they exploit weaknesses that security tools don’t yet know about.