CISA Adds Actively Exploited Zimbra CVE-2026-73570 to KEV Catalog with Immediate Patching Deadline
CISA has added the vulnerability CVE-2026-73570 in Zimbra Collaboration Suite to its Known Exploited Vulnerabilities catalog and mandated immediate mitigation. The defect permits remote command execution without authentication on servers running the optional zimbra-snmp package with SNMP notifications enabled.
The Agency for Cybersecurity and Infrastructure Security of the United States has directed federal civilian agencies to apply the fix urgently. Although the directive targets U.S. federal entities, it effectively places maximum priority on any organization operating Zimbra servers exposed to the internet and processing inbound mail from untrusted networks.
The issue enables unauthenticated remote command execution. Exploitation requires the administrator to have installed the optional zimbra-snmp package and enabled SNMP notifications. In this configuration, an attacker can send manipulated SMTP requests that trigger operating-system-level command injection, executing arbitrary commands with the privileges of the zimbra user.
Zimbra corrected the flaw in Zimbra Collaboration Suite 10.1.20, released on July 20, 2026. CISA added the vulnerability to the KEV catalog on August 21, 2026, a step typically reserved for actively exploited issues. The agency set an August 24, 2026 mitigation deadline for the FCEB environment, underscoring the operational risk.
After patching, administrators should verify the version change, perform a controlled service restart, and confirm stability. If intrusion is suspected, further response includes searching for persistence mechanisms, reviewing authentication anomalies, analyzing unusual outbound connections, and rotating associated credentials.
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