CVE-2026-93629
Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar REQUEST Organizer Identity
- State
- Published
- Severity
- 5.3 Medium
- Published
- Oct 23, 2026
- Updated
- Oct 28, 2026
- Reserved
- Sep 18, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.3 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | rapid7 |
Weaknesses
- CWE-290 Authentication bypass by spoofing
Affected Products
| Product | Versions |
|---|---|
Zimbra Collaboration SuiteZimbra |
|
References
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