Microsoft Reports Severe Zero-Day Flaw in On-Prem Exchange Servers (infosecurity-magazine.com)

• Zero-day in on-prem Exchange Server (2016, 2019, Subscription Edition)
• Unauthenticated remote code execution
• No patch available; active exploitation

"Microsoft disclosed a zero-day vulnerability in on-premises Exchange Server (2016, 2019, and Subscription Edition) allowing unauthenticated remote code execution. Active exploitation has been detected. No patch is yet available. Organizations are urged to apply mitigation measures immediately."