Microsoft catches hackers exploiting Zimbra bug before disclosure

Attackers were poking at a critical Zimbra mail server bug weeks before it was publicly disclosed, and then moved on to steal credentials, raid mailboxes, and take deeper control of compromised systems. Microsoft Threat Intelligence said it tracked exploitation of CVE-2026-73570, an unauthenticated command injection vulnerability in Zimbra Collaboration Suite that gives attackers a potentially easy route into exposed mail servers. No stolen password or unfortunate employee clicking a dodgy link