Disclosure summary
Zimbra Collaboration Suite (ZCS) contains an OS command injection vulnerability which could allow an unauthenticated attacker to send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.
CISA remediation guidance
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.
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
Microsoft Security Blog · RSS-ed93846ffe2d2ac8591f6833ae1ea3527bc
Open original source · Updated Sep 30, 2026
Unauthenticated command injection on internet-facing mail servers: tracking CVE-2026-73570
CVE mention in publisher metadata; check the original affected versions.
Rapid7 Blog · RSS-087d9d059be8baf7b6734d576c5516c0ae3
Open original source · Updated Sep 24, 2026
When Business Email Compromise Starts Rewriting Reality
CVE mention in publisher metadata; check the original affected versions.
Original records & references
PUBLISHED 2026-08-21T00:00:00-04:00
MODIFIED 2026-08-21T00:00:00-04:00
INGESTED 2026-10-06T11:42:57-04:00