Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar REQUEST Organizer Identity (Zimbra Zimbra Collaboration Suite)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.27 % · percentile 19 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- rapid7
- NVD status
- Undergoing Analysis
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.
Weaknesses (CWE)
- CWE-290 — Authentication Bypass by Spoofing
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | rapid7 |
| CVSS 3.1 | MEDIUM 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N | NVD · cve@rapid7.com (Secondary) |
European references
- ENISA EUVD · EUVD-2026-108965
- GCVE · GCVE-0-2026-93629
Affected products
| Product | Versions |
|---|---|
| Zimbra · Zimbra Collaboration Suite | affected 0 ≤ 10.1.21 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |