Is It On KEV?

Synacor Zimbra Collaboration Suite (ZCS)

YES - ON THE CISA KEV LIST
CVE-2026-73570

Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

CISA catalog due date2026-08-24
79 days past due
EPSS exploit probability (next 30 days)76.6% · 100percentile
From CVE publication to KEV listing8 days (2026-08-13 → 2026-08-21)
Remediation window (KEV listing to due date)3 days
Days on the KEV list82 days
Date added to KEV2026-08-21
Known ransomware campaign useUnknown
VendorSynacor
ProductZimbra Collaboration Suite (ZCS)
Weaknesses (CWE)CWE-78

Synacor: 19 entries (1.1% of all KEV entries are from this vendor); 5 added in 2026.

BOD 26-04 note: this is the date printed in the CISA catalog. A federal agency's actual deadline is set by its SSVC tier - Act (3 days), Attend (14 days), Track (60 days), or the next scheduled upgrade - counted from the KEV listing date or the date the vulnerability is identified in its environment, whichever comes first. Use the tier helper on each CVE page for your own window.

Your BOD 26-04 window (SSVC tier helper)

Your remediation window ends:

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 (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.

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

References

Other KEV entries for this vendor: Synacor

Synacor - Vendors with KEV entries

Go deeper

KEV deadlines are a governance problem as much as a patching one. TrebSec's AI governance packs help small teams document, assign, and evidence exactly this work.

AI Governance Policy Pack - $79 AI Vendor Workbook - $49 Both packs bundled - $99

Daily threat briefs at trebsec.com

Check another CVE