CVE-2026-93642: Zimbra Collaboration Suite ZCS

Critical severity, CVSS 9.3. EPSS: 0.2% chance of exploitation in the next 30 days.

An unauthenticated sender can forge a share notification that triggers stored XSS when a signed-in Zimbra Modern recipient clicks Accept Share, allowing the attacker to access mailbox data and act as the victim.

Affected products

• Zimbra Zimbra Collaboration Suite ZCS: before 10.1.21 (fixed in 10.1.21)

Published 2026-09-25. Last modified 2026-09-29.