Cybersecurity briefing — 2026-04-26

Two zero days are being actively exploited right now, and one of them turned an AI demo platform into a malware delivery point in under ten hours.

• GopherWhisper Turns Collaboration Tools Into Espionage Channels
• Teams Trust Turned Into Browser Persistence
• Signed Adware Turns Update Channels Into AV Killers
• FortiClient EMS Hotfixes Leave Uncertainty for 8.0 Users
• Nginx UI’s MCP Endpoint Opens Full Server Takeover
• Marimo Zero-Day Turns AI Demo Hosting Into Malware Delivery
• Simulation Sabotage Malware May Have Preceded Stuxnet
• Black Shrantac Turns Perimeter Flaws Into Quiet Extortion
• F5 BIG-IP APM Flaw Reclassified as Critical RCE with Active Exploitation