What is CVE-2026-93627?

CVE-2026-93627 is a medium-severity vulnerability in Zimbra Collaboration Suite, classified under Authentication Bypass by Spoofing. CVSS score: 5.3/10. Published 2026-10-23.

How severe is CVE-2026-93627?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Zimbra Collaboration Suite

CVE-2026-93627

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 An attacker who knows the meeting UID and organizer address can supply a non-outdated sequence number to move the recipient's meeting to Trash or replace its details.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.

Published 2026-10-23 · last modified 2026-10-23.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Zimbra Collaboration Suite

Weakness classification (CWE)

CWE-290 — Authentication Bypass by Spoofing

References

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

Frequently asked questions

What is CVE-2026-93627?: CVE-2026-93627 is a medium-severity vulnerability in Zimbra Collaboration Suite, classified under Authentication Bypass by Spoofing. CVSS score: 5.3/10. Published 2026-10-23.
How severe is CVE-2026-93627?: Medium severity. CVSS v3 base score is 5.3 out of 10.