CVE WatchAug 24, 2026

CVE-2026-73570

Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

CVSS

8.9

High

EPSS

11.7%

p96

KEV

YES

Aug 21, 2026

Exploit Today

0-100

Published: Aug 13, 2026 · Last modified: Aug 24, 2026 · CWE-78

EPSS · 30d

11.7%EPSS · 30 days32.4%

2026-08-302026-09-27

KEV catalog record

Product

Synacor / Zimbra Collaboration Suite (ZCS)

Vulnerability

Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

Added to KEV

Aug 21, 2026

Remediate by

Aug 24, 2026

Known ransomware use

Summary description

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.

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.

Notes

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://blog.zimbra.com/2026/07/patch-release-update-zimbra-10-1-20/ ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-73570

Technical description

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.

Official references

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