# CVE-2026-78359: Duplicate Identity / Identity Shadowing across CustomerUser backends

> Authenticated users with customer management permissions can create duplicate identities across backends, leading to data exposure or misrouting.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-49rp-wmg4-84xg, UBUNTU-CVE-2026-78359

## What is CVE-2026-78359?

CVE-2026-78359 is a medium-severity vulnerability in ((OTRS)) Community Edition, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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

Weakness: CWE-706 (Use of Incorrectly-Resolved Name or Reference), CWE-694 (Use of Multiple Resources with Duplicate Identifier)

## Which versions are affected by CVE-2026-78359?


## How do I fix CVE-2026-78359?

No fix has been published for CVE-2026-78359 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-78359 being exploited?

There is no known exploitation of CVE-2026-78359 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78359 and fix it if it is affected.

What it is: CVE-2026-78359 is a medium-severity vulnerability in ((OTRS)) Community Edition, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-78359 in the wild and no public exploit code.

Affected product: ((OTRS)) Community Edition. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-78359/ (Markdown: https://insights.sbomify.com/CVE-2026-78359/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78359
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78359
- OSV: https://osv.dev/vulnerability/CVE-2026-78359

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78359/
Summaries are generated and may contain mistakes; the official description above is the record.