CVE-2026-115786

A mailbox quota-accounting vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to consume another user’s mailbox quota by repeatedly sharing and revoking a document. Creation of the recipient’s shared-file record charges the document size to mailbox-wide usage. Revocation deletes the record and reverses its folder counters without reversing the mailbox-wide charge. Repeated normal share notifications therefore accumulate quota usage after the visible records are gone. On accounts with a finite quota, this can prevent incoming mail and other size-increasing operations without recipient interaction. The issue affects ZCS 10.1.16 and 10.1.20.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

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

Configurations

No configuration.

History

23 Oct 2026, 14:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-23 14:17

Updated : 2026-10-28 20:17

NVD link : CVE-2026-115786

Mitre link : CVE-2026-115786

CVE.ORG link : CVE-2026-115786

JSON object : View

Products Affected

No product.

CWE

CWE-682

Incorrect Calculation

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