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CVE-2026-73570: Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

Synacor Zimbra Collaboration Suite (ZCS) · in CISA KEV since 2026-08-21

2026-08-21added to KEV

2026-08-24federal remediation due date

32.38%EPSS exploit probability (30 days) 98.3th percentile

8.9 HIGHCVSS 3.1

Unknownknown ransomware use

8days from NVD publication to KEV

What it is

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 (CISA)

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.

CWE	CWE-78
CVSS vector	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L`
NVD published	2026-08-13 (Analyzed)

Original records: NVD · CISA KEV · JSON: /api/cve/CVE-2026-73570.json · all KEV CVEs

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