Exploited vulnerability CISA KEV
CVE-2026-73570: Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
CVE-2026-73570 is a vulnerability in Synacor Zimbra Collaboration Suite (ZCS) that CISA added to its Known Exploited Vulnerabilities catalog on August 21, 2026, meaning there is evidence it is being exploited. US federal civilian agencies must complete the required action by August 24, 2026.
CVE-2026-73570 is a vulnerability in Synacor Zimbra Collaboration Suite (ZCS) that CISA added to its Known Exploited Vulnerabilities catalog on August 21, 2026, meaning there is evidence it is being exploited. US federal civilian agencies must complete the required action by August 24, 2026.
- CVE ID
- CVE-2026-73570
- Vendor / project
- Synacor
- Product
- Zimbra Collaboration Suite (ZCS)
- Added to KEV
- Due date
- Days to remediate
- 3
- Known ransomware use
- Unknown
- Weakness
- CWE-78
CISA 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 and references #
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
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