---
id: CVE-2026-93636
title: >-
  Zimbra Collaboration Suite LDAP Filter Injection via Calendar Resource
  Attribute Name
summary: >-
  An LDAP filter injection vulnerability in Zimbra Collaboration Suite (ZCS)
  allows an authenticated user to query otherwise unreturned attributes of
  calendar resources through SearchCalendarResourcesRequest. Zimbra escapes
  search values b…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-90
vendor: Zimbra
product: Zimbra Collaboration Suite
affected:
  - collaboration_suite <= 10.1.21
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T13:27:14.020Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-93636'
references:
  - url: 'https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories'
  - url: >-
      https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/
tags:
  - cve.org
ingestedAt: '2026-10-23T14:28:08.711Z'
---

## Overview

An LDAP filter injection vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to query otherwise unreturned attributes of calendar resources through SearchCalendarResourcesRequest. Zimbra escapes search values but inserts the supplied attribute names directly into LDAP filter expressions without validation. An attacker can inject additional conditions and use repeated matching queries to recover readable resource attributes such as internal mailbox hostnames and mail transport routes. The search remains restricted to calendar-resource objects and the LDAP service account's access rights. ZCS 10.1.16 and 10.1.21 are affected.

## Affected

- `collaboration_suite <= 10.1.21`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.