What is CVE-2026-93634?

CVE-2026-93634 is a medium-severity vulnerability in Zimbra Collaboration Suite, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-10-23.

How severe is CVE-2026-93634?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Zimbra Collaboration Suite

CVE-2026-93634

A cross-account authorization vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to insert forged shared-file records into another user's mailbox through FileSharedWithMeRequest. The request bypasses delegated-account authorization and accepts attacker-selected file metadata, owner identifiers and declared sizes without validating a corresponding document share. An attacker can plant entries attributed to another real local account without that account sharing a document. No victim interaction is required. ZCS 10.1.16 and 10.1.20 are affected.

Vulnerability class: IDOR (Insecure Direct Object Reference)

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

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/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-639 — Authorization Bypass Through User-Controlled Key

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-2026-93634?: CVE-2026-93634 is a medium-severity vulnerability in Zimbra Collaboration Suite, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-10-23.
How severe is CVE-2026-93634?: Medium severity. CVSS v3 base score is 4.3 out of 10.