Critical Zero-Days in Cisco, Chrome, and WatchGuard Actively Exploited; React2Shell Weaponized for Ransomware

This cybersecurity brief for December 19, 2025, covers a surge in critical vulnerability exploitation. Multiple threat actors are leveraging the React2Shell flaw (CVE-2025-55182) to deploy ransomware. Concurrently, a China-linked APT is exploiting a zero-day in Cisco email gateways (CVE-2025-20393), and actively exploited flaws in WatchGuard firewalls and Google Chrome are putting networks and users at severe risk. Other major incidents include critical patches for HPE OneView, significant data breaches at SoundCloud and 700Credit, and new regulatory updates from the UK.