Synacor · Zimbra Collaboration Suite (ZCS)
CVE-2026-73570
Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
What it is
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.
CISA: 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.
What to do
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.
Deadline for US federal agencies: August 24, 2026
More exploited flaws from Synacor
| Added | Vulnerability | Product | Severity | Attack chance |
|---|---|---|---|---|
| Apr 20, 2026 | Cross-site Scripting | Zimbra Collaboration Suite (ZCS) | Medium 6.1 | 1.7% |
| Mar 18, 2026 | Cross-Site Scripting | Zimbra Collaboration Suite (ZCS) | High 7.2 | 20% |
| Oct 7, 2025 | Cross-site Scripting | Zimbra Collaboration Suite (ZCS) | Medium 5.4 | 4.1% |
| Jul 7, 2025 | Server-Side Request Forgery (SSRF) | Zimbra Collaboration Suite (ZCS) | High 7.5 | 81% |
| May 19, 2025 | Cross-Site Scripting (XSS) | Zimbra Collaboration Suite (ZCS) | Medium 6.1 | 25% |
| Feb 25, 2025 | Cross-Site Scripting (XSS) | Zimbra Collaboration Suite (ZCS) | Critical 9.0 | 77% |
| Oct 3, 2024 | Command Execution | Zimbra Collaboration Suite (ZCS) | Critical 10.0 | 99.9% |
| Jul 27, 2023 | Cross-Site Scripting (XSS) | Zimbra Collaboration Suite (ZCS) | Medium 6.1 | 49% |
Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.