Medium severity · published Oct 23, 2026
CVE-2026-93634
Zimbra Collaboration Suite Cross-Account Authorization Bypass via Forged Shared-File Records
New
4.3
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 13% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
Collaboration · Zimbra
through 10.1.20 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-93634
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-93634
wiki.zimbra.com
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
www.rapid7.com
https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/
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