Exploited vulnerabilities / CVE-2026-73570
Confirmed exploited · command injection · Synacor Zimbra Collaboration Suite (ZCS)CVE-2026-73570
Synacor Zimbra Collaboration Suite (ZCS) command injection, confirmed exploited in the wild.
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.
| CISA's name for it | Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability |
|---|---|
| Vendor and product | Synacor · Zimbra Collaboration Suite (ZCS) |
| Type | command injection · CWE-78 |
| Exploited | Confirmed by CISA listed 21 August 2026 |
| Likelihood | one of the most likely to be exploited of every vulnerability tracked |
| Deadline | 24 August 2026 · already passed |
| Used in ransomware | Not reported |
| Advisories | wiki.zimbra.com ↗ · blog.zimbra.com ↗ · www.cisa.gov ↗ · www.cisa.gov ↗ |
Three steps, in this order
Apply the vendor fix; command injection on an exposed device is used within days of disclosure.
Restrict the management interface to a trusted network until the fix is in.
Review the device's logs and configuration for changes you did not make.
| CISA's 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. |
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Know before someone else finds it
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CVE-2026-73570 in short
Is CVE-2026-73570 being exploited?
Yes. CISA added CVE-2026-73570 to its Known Exploited Vulnerabilities catalogue on 21 August 2026, which it does only on evidence of exploitation in the wild.
What is the CISA deadline for CVE-2026-73570?
US federal agencies must remediate it by 24 August 2026. Everyone else should treat that date as the latest safe point to patch an internet-facing system.
How likely is CVE-2026-73570 to be exploited in the next 30 days?
FIRST's Exploit Prediction Scoring System gives it 77%, the 99th percentile of every CVE it scores.
How do I fix CVE-2026-73570?
Apply the vendor fix; command injection on an exposed device is used within days of disclosure. Restrict the management interface to a trusted network until the fix is in. Review the device's logs and configuration for changes you did not make.
Other Synacor vulnerabilities being exploited
| CVE | Product | Type | Listed |
|---|---|---|---|
| CVE-2025-48700 | Zimbra Collaboration Suite (ZCS) | cross-site scripting | 20 April 2026 |
| CVE-2025-66376 | Zimbra Collaboration Suite (ZCS) | cross-site scripting | 18 March 2026 |
| CVE-2020-7796 | Zimbra Collaboration Suite | server-side request forgery | 17 February 2026 |
| CVE-2025-68645 | Zimbra Collaboration Suite (ZCS) | exploited vulnerability | 22 January 2026 |
Sources: CISA Known Exploited Vulnerabilities catalogue (released 10 November 2026) and FIRST EPSS. Page compiled automatically by SAK T.L.M, the threat-intelligence tool of SAK T.E.C, on 13 November 2026.