LDAP Filter Injection in Zimbra C&S via SearchCalendarResources (10.1.16/21)
CVE-2026-93636 Published on October 23, 2026
Zimbra Collaboration Suite LDAP Filter Injection via Calendar Resource Attribute Name
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.
Vulnerability Analysis
CVE-2026-93636 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
What is a LDAP Injection Vulnerability?
The software constructs all or part of an LDAP query using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended LDAP query when it is sent to a downstream component.
CVE-2026-93636 has been classified to as a LDAP Injection vulnerability or weakness.
Products Associated with CVE-2026-93636
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Affected Versions
Zimbra Collaboration Suite:- Before and including 10.1.21 is affected.