CVE-2026-93628

The Zimbra Collaboration Suite (ZCS) version 10.1.16 and 10.1.21 are vulnerable to an authentication bypass in the email calendar processing. The root cause is that the system passes a null sender identity when processing iCalendar REPLY components, which leads to the attendee authorization filte...

EUVD-2026-108964

An attendee authentication vulnerability in the email calendar processing of Zimbra Collaboration Suite ZCS allows an unauthenticated sender to forge another attendee's response to an existing meeting. Zimbra passes a null sender identity when processing iCalendar REPLY components, causing the...

CVE-2026-93627

The Zimbra Collaboration Suite (ZCS) versions 10.1.16 and 10.1.21 are vulnerable to an authentication bypass in the email calendar processing component. The root cause is that the system accepts iCalendar CANCEL and REQUEST components without verifying if the email sender is authorized to act as ...

EUVD-2026-108963

An organizer authentication vulnerability in the email calendar processing of Zimbra Collaboration Suite ZCS allows an unauthenticated sender to cancel or modify an existing meeting in a recipient's calendar. Zimbra accepts iCalendar CANCEL and REQUEST components without verifying that the email...