PatchTheCVECVE-2026-93629: An organizer authentication vulnerability in Zimbra Collaboration Suite (ZCS) allows an unauthenticated email
CVE-2026-93629 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 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
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-2026-93629?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-93629 being exploited?
CVE-2026-93629 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-2026-93629 affect?
CVE-2026-93629 affects affected software. Severity is medium (CVSS 5.3). 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 no
How urgent is CVE-2026-93629?
Priority 31/100. Remotely exploitable, no login, no user action