CVE-2026-93647: critical vulnerability in Zimbra Collaboration Suite (ZCS)
Zimbra Collaboration Suite Classic Web Client Stored Cross-Site Scripting via Crafted Calendar COUNTER Message From Address
Published · Updated
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28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.3epss 0.2%
An unauthenticated calendar sender can place active markup in a COUNTER message's RFC From address. Selecting the message in Zimbra Classic triggers stored XSS, allowing the attacker to access mailbox data and act as the victim.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Affected products
Zimbra · Zimbra Collaboration Suite (ZCS)Related CVEs — Zimbra Collaboration Suite (ZCS)
In the same product, most dangerous first.
CVE-2026-93643CRITICALZimbra Collaboration Suite OnlyOffice Integration Path Traversal Leading to Remote Code Execution via Unauthenticated /downloadas RequestEPSS 1.0%CVE-2026-93641CRITICALZimbra Collaboration Suite Classic Web Client Stored Cross-Site Scripting via Forged Share InvitationEPSS 0.3%CVE-2026-93642CRITICALZimbra Collaboration Suite Modern Web Client Stored Cross-Site Scripting via Forged Share InvitationEPSS 0.2%