Vulnerability in Zimbra Collaboration Suite (ZCS)

[ Why it matters ]Priority signals

• Critical severity: CVSS 9.8

[ Description ]Official description

When OnlyOffice/Document Editing is available, an unauthenticated remote attacker with access to an existing supported public Briefcase document can abuse unsigned save fields to perform path-traversal writes and execute commands as zimbra.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• BSI CERT-Bund27 Sep 2026WID-SEC-2026-3593

  Synacor Zimbra: Multiple vulnerabilities Translated from German

  CVE-2026-93647CVE-2026-66912CVE-2026-66911+3 more CVEs

[ References ]References

• wiki.zimbra.com/wiki/Zimbra_Security_Advisories