CVE-2026-93634

EUVD-2026-108974

23.10.2026, 14:17

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.

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
rapid7	CNA	4.3 MEDIUM	NETWORK	LOW	LOW	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Base Score

CVSS 3.x

EPSS Score

Percentile: Unknown

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources.

Vendor	Product	Version	Source
zimbra	collaboration	𝑥 ≤ 10.1.20	CNA

Common Weakness Enumeration

CWE-639 - Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

References

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories

https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/