An organizer authentication vulnerability in Zimbra Collaboration Suite (ZCS) allows an unauthenticated email sender to insert calendar invitations attributed to another user. The email delivery path permits external invitations but does not verify that the message sender is authorized to use the iCalendar ORGANIZER identity. When automatic invitation insertion is enabled, a crafted REQUEST component creates an event containing attacker-selected meeting details and reminders under a forged organizer without recipient interaction. No corresponding event is created in the claimed organizer's calendar. ZCS 10.1.16 and 10.1.21 are affected.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 9
- StatusUndergoing Analysis → PublishedNVD modified 2026-10-28 19:51
- StatusPublished → Undergoing AnalysisNVD modified 2026-10-28 20:18
- StatusUndergoing Analysis → PublishedNVD modified 2026-10-28 19:51
- StatusPublished → Undergoing AnalysisNVD modified 2026-10-28 20:18
- StatusAwaiting Analysis → PublishedNVD modified 2026-10-23 13:19
- StatusPublished → Awaiting AnalysisNVD modified 2026-10-23 16:44
- StatusReceived → PublishedNVD modified 2026-10-23 13:19
- StatusPublished → ReceivedNVD modified 2026-10-23 14:17
- First seenCVSS 5.3 · zimbraNVD modified 2026-10-23 13:19
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.