Threat actors are actively exploiting CVE-2026-73570 (CVSS 8.9), a now-patched unauthenticated operating system command injection flaw in Zimbra Collaboration Suite (ZCS). Microsoft Security Research team findings indicate that attackers are leveraging this vulnerability to deploy web shells and gain access to mailbox data. The flaw, which can lead to remote code execution via Simple Network Management Protocol (SNMP), highlights the importance of timely patching for email and collaboration platforms. Organizations using Zimbra should ensure their systems are updated and investigate for signs of compromise.