Zimbra Collaboration Suite's OS Command Injection Allows Authenticated Attackers to Execute Arbitrary Commands on the Email Server with Elevated Privileges; CISA's August 24th KEV Deadline Has Passed

Last refreshed2026-09-27

Status: KEV | Advisory ID: CVE-2026-73570

Key Details

CVE	CVE-2026-73570
Vulnerability Name	Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
CVSS Score / Version	8.9 (High) / CVSS v3.1
Updated	2026-09-22
CVSS Vector	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L`
CVSS Prose	attack vector is network; attack complexity is high; privileges required is none; user interaction is none; scope is changed; confidentiality impact is high; integrity impact is high; availability impact is low.
Affected products	Synacor Zimbra Collaboration Suite (ZCS) and Synacor Zimbra Collaboration Suite
Exploitation status	Listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation.
Classified as	CWE-78 (Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'))
KEV listing	Added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-08-21.
Exploitation prediction (EPSS)	11.74% probability of exploitation in the next 30 days (96% percentile) -- FIRST.org's EPSS model.
Federal remediation deadline	2026-08-24 (CISA KEV, Binding Operational Directive).

Affected Products, Subsystems & Sectors

Vendor	Product	Affected Versions	Patch Status
Synacor	Zimbra Collaboration Suite (ZCS)
Synacor	Zimbra Collaboration Suite

Vendor

Product

Affected Versions

Patch Status

Synacor

Zimbra Collaboration Suite (ZCS)

Synacor

Zimbra Collaboration Suite

Subsystems	General OT
Sectors	Multiple

What to Know

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.

What to Do

Monitor Synacor's web page for any future patch releases.

References

Source	Reference
NVD	https://nvd.nist.gov/vuln/detail/CVE-2026-73570
CVE	https://www.cve.org/CVERecord?id=CVE-2026-73570

Source

Reference

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-73570

CVE

https://www.cve.org/CVERecord?id=CVE-2026-73570

KEV Required Action

Field	Value
KEV Link	https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Date Added to KEV	2026-08-21
Required Action Due Date	2026-08-24
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.

Field

Value

KEV Link

https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Date Added to KEV

2026-08-21

Required Action Due Date

2026-08-24

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.