Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Zimbra Collaboration Suite (ZCS), fix it now.
CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
US federal civilian agencies must remediate by Aug 24, 2026.
Official fix available since
Apply the vendor's update to every affected system. Check the fixed-in versions below where known.
Basis: Microsoft Security Blog & MSRC vendor advisory
A remote code execution vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.20 when the optional zimbra-snmp package is installed and SNMP notifications are enabled. Due to improper sanitization of untrusted input during SNMP notification processing, an unauthenticated attacker can send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
| Product | Vendor | Affected versions | Fixed in | Source |
|---|---|---|---|---|
| Zimbra Collaboration Suite | Synacor | < 10.1.20 | 10.1.20 | NVD |
| Zimbra Collaboration Suite (ZCS) | Synacor | — | — | KEV |
Sources: NVD = NIST National Vulnerability Database; KEV = CISA Known Exploited Vulnerabilities catalog.
Developments from the last 30 days, newest first.
Patch released for CVE-2026-73570: Synacor Zimbra Collaboration Suite (ZCS), Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
An official fix is now available for Synacor Zimbra Collaboration Suite (ZCS). This vulnerability is being exploited, so apply it promptly.
Basis: Microsoft Security Blog & MSRC vendor advisory
1 earlier event is available with a subscription. See plans.
CISA lists this as exploited in the wild. Unpatched Zimbra Collaboration Suite (ZCS) systems are exposed to active attacks now.
Apply the vendor's security update for Zimbra Collaboration Suite (ZCS).
