CVE-2026-93627Medium· 5.3▾ SunlitAn 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 C…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 29.2 · likelihood 0 · exploitation 0
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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 An attacker who knows the meeting UID and organizer address can supply a non-outdated sequence number to move the recipient's meeting to Trash or replace its details.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.
collaboration_suite <= 10.1.21Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-93629Medium· 5.3Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar REQUEST Organizer Identity
CVE-2026-93628Medium· 5.3Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar REPLY Attendee Response
CVE-2026-93631High· 7.1Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account Linking
CVE-2026-93630Medium· 4.3Zimbra Collaboration Suite Email HTML Sanitizer Bypass via Hostname Canonicalization
CVE-2026-93636Medium· 4.3Zimbra Collaboration Suite LDAP Filter Injection via Calendar Resource Attribute Name
CVE-2026-93633Medium· 5.4Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Characters