RCE in Synacor Zimbra Collaboration Suite
CVE-2026-73570
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.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.9 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:L.
EPSS exploit prediction
EPSS: 0.117 (95.9th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 96th percentile — 95.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.205 · newest: 0.117 · change: -0.088
Affected products
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
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.
Public proof-of-concept exploits
References
- wiki.zimbra.com/wiki/Zimbra_Security_Advisories (Vendor Advisory)
- wiki.zimbra.com/wiki/Security_Center (Release Notes)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Third Party Advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)
Frequently asked questions
- What is CVE-2026-73570?
- CVE-2026-73570 is a high-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under OS Command Injection. CVSS score: 8.9/10. Published 2026-08-13.
- How severe is CVE-2026-73570?
- High severity. CVSS v3 base score is 8.9 out of 10.
- Is CVE-2026-73570 known to be exploited?
- Yes. CVE-2026-73570 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-08-21), indicating it is being actively exploited. 8 public proof-of-concept repositories are indexed.