Risk Letters

Exploited vulnerability

CVE-2026-73570

TLP:CLEAR

Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

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.

Facts

  • Vendor: Synacor
  • Product: Zimbra Collaboration Suite (ZCS)
  • CVSS: 8.9
  • EPSS (probability of exploitation within 30 days): 71.7 %
  • On CISA's Known Exploited Vulnerabilities list since: 21 August 2026
  • First known exploitation: 21 August 2026
  • CISA's deadline for US federal agencies: 24 August 2026
  • Weakness: CWE-78
  • First seen by Risk Letters: 25 August 2026

Members see which Nordic sectors the flaw hits, and what to do about it.

Get the full brief

Data: NVD (public domain), CISA KEV, FIRST EPSS, MITRE ATT&CK, AlienVault OTX. NVD