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.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Sources
Also known as GHSA-49rp-wmg4-84xg, UBUNTU-CVE-2026-78359.