Hackers Target Zimbra Servers in Active Exploitation Campaign

The active exploitation of CVE-2026-73570 in Zimbra Collaboration servers highlights the critical danger of delayed patching on internet-facing infrastructure. This high-severity vulnerability allows unauthenticated attackers to execute arbitrary OS commands, meaning no credentials are required to achieve full server compromise. Organizations running unpatched Zimbra instances are exposed to credential harvesting, lateral movement, and potentially nation-state-level intrusion. The speed at which threat actors — historically including Russian and Chinese APT groups — exploit known Zimbra flaws underscores that patch windows are shrinking and that email servers represent high-value, high-exposure targets.