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Please read carefully and check if the version of your Zammad system is affected by this vulnerability. Please send information regarding vulnerabilities in Zammad to: security at

Security Advisory Details

Vulnerability Descriptions

Unverified Customer can self-assign to unauthorized Organization

An attacker can register a new account with a non existing email address containing the domain of an existing Organization. After that the attacker will be able to login to the interface. If the "shared Organization" feature is active (default: yes) and the "domain based assignment" feature is active too (default: no) the attacker will have access to all the Tickets of the Organization. This comes without the need to verify the email address.

Special 🙏 and 🤘 and ❤️ to:

N: Björn Engels
D: Cloud Architect

Recommended Resolution

This vulnerability is fixed in the latest versions of Zammad and it is recommended to upgrade to one of these.

Fixed releases can be found at:

Or just update your Zammad if installed via OS package manager.

Additional information

Online version of this advisory:

Send all remarks to security issues to security @