PatchTheCVECVE-2026-93627: An organizer authentication vulnerability in the email calendar processing of Zimbra Collaboration Suite (ZCS)
CVE-2026-93627 is a medium-severity flaw (CVSS 5.3) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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 An attacker who knows the meeting UID and organizer address can supply a non-outdated sequence n
Why this priority
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.4% (top 70%) |
| CISA exploited list | No |
| Weakness | CWE-290 |
| Published | 2026-10-23 |
| Last modified | 2026-10-23 |
Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-93627?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-93627 being exploited?
CVE-2026-93627 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-93627 affect?
CVE-2026-93627 affects affected software. Severity is medium (CVSS 5.3). 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 CANC
How urgent is CVE-2026-93627?
Priority 31/100. Remotely exploitable, no login, no user action