Security Operations
Threat Intelligence
๐Ÿ”Ž
โ“

CVE-2026-93629 - An organizer authentication vulnerability in Zimbra Collaboration Suite (ZCS) allows an unauthenticated email sender to

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.
MEDIUM
Severity & confidence
Source severitymedium
Platform severitymedium
Confidencehigh
Exploitationunknown
CVSS5.3
Affected
Reporting sources (1)
NIST NVD - National Vulnerability Database
Open source โ†—
Timeline & provenance
Published2026-10-23T14:17:56
Last updated2026-10-26T14:17:11
Ingested2026-10-25T19:54:40
FreshnessNEAR-REAL-TIME
Threat typevulnerability
Recommended action
No recommended action published with this item - review the original source.
Next steps
  1. Identify affected systems in your environment.
  2. Apply the vendor patch or mitigation guidance.
  3. Review logs for indicators described in the advisory.
  4. Follow the affected vendor/product to track updates.
Confidence explanation
Reported by a government or cert-grade source (CISA, NCSC, NVD, ENISA, MSRC).
Source type: standards ยท Original: NIST NVD - National Vulnerability Database