CVE-2026-93627 (GCVE-0-2026-93627)

Vulnerability from cvelistv5 – Published: 2026-10-23 13:17 – Updated: 2026-10-28 20:02
VLAI
Title
Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar CANCEL/REQUEST Organizer
Summary
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 sender is authorized to act as the supplied organizer. An attacker who knows the meeting UID and organizer address can supply a non-outdated sequence number to move the recipient's meeting to Trash or replace its details. Processing occurs automatically during email delivery without recipient interaction. ZCS 10.1.16 and 10.1.21 are affected.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-28 18:23 UTC
CWE
  • CWE-290 - Authentication bypass by spoofing
Assigner
rapid7 CNA under the mitre root
CNA scorecard B 76/100 over 82 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Zimbra Zimbra Collaboration Suite Affected: 0 , ≤ 10.1.21 (semver)
guessed Create a notification for this product.
Date Public
2026-10-23 12:44
Credits
Jonah Burgess (CryptoCat), Senior Security Researcher, Rapid7
Show details on NVD website
To clipboard 

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