Vulnerabilities / CVE-2026-93629

CVE-2026-93629

Published 2026-10-23 · published (not yet in NVD)

CVE-2026-93629

Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar REQUEST Organizer Identity

5.3 MEDIUM
CVSS 3.1 · CNA

0.3%
chance of exploitation in the next 30 days (EPSS; higher than 19% of CVEs)

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

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NCNA

Affected products

Zimbra Zimbra Collaboration Suite: 0 to ≤ 10.1.21

Weakness: CWE-290

2 references (advisories, patches, write-ups)

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories · vendor-advisory
https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/ · related

Sources: CVE.org, FIRST EPSS. Missing ones did not answer or have no record yet.

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