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CVE-2026-115786— Zimbra Collaboration Suite Shared-File Mailbox Quota Accounting Error Enables Quota Exhaustion

Quick assessment

Affected
Zimbra Zimbra Collaboration Suite
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Zimbra 协作套件（ZCS）中存在一个邮箱配额核算漏洞，允许已认证用户通过反复共享和撤销文档，消耗其他用户的邮箱配额。创建收件人的共享文件记录时，会将文档大小计入邮箱整体使用量；而撤销操作虽会删除该记录并重置其文件夹计数器，却不会撤销已计入邮箱整体使用量的配额占用。因此，在重复执行常规共享通知后，即使可见记录已被删除，配额使用量仍会持续累积。在配额有限的账户上，此问题可在无需收件人参与的情况下，阻止新邮件接收及其他增加用量的操作。该漏洞影响 ZCS 10.1.16 和 10.1.20 版本。

CVSS 6.5 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-115786

Vulnerability Information
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Vulnerability Title
Zimbra Collaboration Suite Shared-File Mailbox Quota Accounting Error Enables Quota Exhaustion
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
数值计算不正确
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Zimbra Zimbra Collaboration Suite 0 ~ 10.1.20 -

II. Public POCs for CVE-2026-115786

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III. Intelligence Information for CVE-2026-115786

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Vendor Advisories for CVE-2026-115786 (1)

Other References for CVE-2026-115786 (1)

Same Patch Batch · Zimbra · 2026-10-23 · 17 CVEs total

CVE-2026-10632 8.7 HIGH Zimbra Collaboration Suite Classic Web Client Reflected Cross-Site Scripting via Document
CVE-2026-50053 8.7 HIGH Zimbra Collaboration Suite RestFilter Request Attribute Override via Unauthenticated URL P
CVE-2026-93639 8.7 HIGH Zimbra Collaboration Suite Missing Authorization in ConfigureZimlet Enables Delegated Admi
CVE-2026-93640 7.8 HIGH Zimbra Collaboration Suite Local Privilege Escalation via Unrestricted zmunbound Sudo Conf
CVE-2026-50056 7.8 HIGH Zimbra Collaboration Suite Local Privilege Escalation via zmmailboxdmgr JVM Argument Injec
CVE-2026-50057 7.8 HIGH Zimbra Collaboration Suite Local Privilege Escalation via Unrestricted Postfix Sudo Permis
CVE-2026-93631 7.1 HIGH Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account Link
CVE-2026-93638 6.1 MEDIUM Zimbra Collaboration Suite Pre-Authentication Reflected Cross-Site Scripting via Login Pag
CVE-2026-93633 5.4 MEDIUM Zimbra Collaboration Suite Briefcase CSS Sanitization Bypass via Non-ASCII Stylesheet Char
CVE-2026-93629 5.3 MEDIUM Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar
CVE-2026-93627 5.3 MEDIUM Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar
CVE-2026-93628 5.3 MEDIUM Zimbra Collaboration Suite Calendar Processing Authentication Bypass via Forged iCalendar
CVE-2026-93630 4.3 MEDIUM Zimbra Collaboration Suite Email HTML Sanitizer Bypass via Hostname Canonicalization
CVE-2026-93634 4.3 MEDIUM Zimbra Collaboration Suite Cross-Account Authorization Bypass via Forged Shared-File Recor
CVE-2026-93636 4.3 MEDIUM Zimbra Collaboration Suite LDAP Filter Injection via Calendar Resource Attribute Name
CVE-2026-115785 4.3 MEDIUM Zimbra Collaboration Suite Data Source Test SMTP Command Injection via Unsanitized Email A

IV. Related Vulnerabilities

Same product: Zimbra Collaboration Suite
Same vendor: Zimbra
Same weakness: CWE-682

V. Comments for CVE-2026-115786

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