AI-generated illustration by CyberShitty. Not a photograph or a document from the organisations named.
On 21 August 2026, CISA added 1 actively exploited vulnerability affecting Synacor to its Known Exploited Vulnerabilities catalog. If you run any of these products, patch or mitigate now — exploitation is already happening.
KEV deadlines bind US federal agencies only, but a listing means attackers are already using the flaw, so treat it as a patch-now signal. If one of these products in your organisation was compromised, CERT-In's directions of 28 April 2022 require service providers, intermediaries, data centres, companies and government organisations to report specified incidents within 6 hours of noticing them. How to report an incident to CERT-In.
The vulnerabilities
CVE-2026-73570Federal deadline
Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
Synacor / Zimbra Collaboration Suite (ZCS) / CWE-78
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. CISA links: BOD 26-04 · Forensics Triage Requirements
