Zero-Day Exploits Surge, Nearly 30% of Flaws Attacked Before Disclosure

VulnCheck's State of Exploitation 2026 report finds that 28.96% of known exploited vulnerabilities were exploited before or on the day of CVE disclosure in 2025 (up from 23.6% in 2024), with 884 vulnerabilities first observed exploited that year; exploitation spanned hundreds of vendors and most frequently targeted network edge devices, content management systems and open source software, while operating systems showed high rates of immediate exploitation.