Description
OTRS does not sufficiently enforce the uniqueness of customer user identities across multiple configured CustomerUser backends. When multiple backends, such as a database and LDAP, are configured, the uniqueness check for customer user email addresses is performed only within the selected backend. As a result, an authenticated user with permission to create or modify customer users may create a customer user whose email address is already assigned to a customer user in another backend.

This can result in multiple customer user records representing the same communication identity. Depending on the affected workflow and backend resolution, customer-related information or email communication may subsequently be associated with or exposed to the wrong customer user.

The vulnerability does not allow unauthenticated users to create customer accounts. Exploitation requires permissions to create or modify customer users.

This issue affects OTRS:

* 7.0.X
* 8.0.X
* 2023.X
* 2024.X
* 2025.X
* 2026.X before 2026.7.X

Please note that ((OTRS)) Community Edition 6.x and before are vulnerable. Products based on the ((OTRS)) Community Edition also very likely to be affected
Published: 2026-10-12
Score: 5.4 Medium
EPSS: n/a
KEV: No
AI Analysis

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Remediation

Vendor Solution

Update to latest version of OTRS (2026.7.1. or later). Please note that there will be no OTRS 7 patches

Tracking

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Advisories

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History

Mon, 12 Oct 2026 07:00:00 +0000

Type Values Removed Values Added
Description OTRS does not sufficiently enforce the uniqueness of customer user identities across multiple configured CustomerUser backends. When multiple backends, such as a database and LDAP, are configured, the uniqueness check for customer user email addresses is performed only within the selected backend. As a result, an authenticated user with permission to create or modify customer users may create a customer user whose email address is already assigned to a customer user in another backend. This can result in multiple customer user records representing the same communication identity. Depending on the affected workflow and backend resolution, customer-related information or email communication may subsequently be associated with or exposed to the wrong customer user. The vulnerability does not allow unauthenticated users to create customer accounts. Exploitation requires permissions to create or modify customer users. This issue affects OTRS: * 7.0.X * 8.0.X * 2023.X * 2024.X * 2025.X * 2026.X before 2026.7.X Please note that ((OTRS)) Community Edition 6.x and before are vulnerable. Products based on the ((OTRS)) Community Edition also very likely to be affected
Title Duplicate Identity / Identity Shadowing across CustomerUser backends
Weaknesses CWE-694
CWE-706
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: OTRS

Published:

Updated: 2026-10-12T06:49:24.983Z

Reserved: 2026-08-24T11:29:41.427Z

Link: CVE-2026-78359

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-12T07:16:37.423

Modified: 2026-10-12T07:16:37.423

Link: CVE-2026-78359

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-12T08:30:07Z

Weaknesses
  • CWE-694

    Use of Multiple Resources with Duplicate Identifier

  • CWE-706

    Use of Incorrectly-Resolved Name or Reference