Open Zaak up to 1.27.1/1.28.1 Search Endpoint _zoek improper authorization

Summaryinfo

A vulnerability identified as problematic has been detected in Open Zaak up to 1.27.1/1.28.1. Affected by this vulnerability is an unknown functionality of the file /zaken/api/v1/zaken/_zoek of the component Search Endpoint. Performing a manipulation results in improper authorization. This vulnerability is identified as CVE-2026-54657. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Open Zaak up to 1.27.1/1.28.1. This affects some unknown functionality of the file /zaken/api/v1/zaken/_zoek of the component Search Endpoint. The manipulation with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality. The summary by CVE is:

Open Zaak is an open-source data and services layer for Dutch case-oriented working. From 1.0.0 until 1.27.2, 1.28.2, and 1.29.0, the POST search endpoints /zaken/api/v1/zaken/_zoek and /documenten/api/v1/enkelvoudiginformatieobjecten/_zoek do not filter result querysets according to the authorizations associated with the request token. A caller with a valid zaken.lezen or documenten.lezen token can therefore retrieve case or document metadata outside the token's authorized types or confidentiality levels. Document searches require known UUIDs, and document content remains protected by separate download authorization. This issue is fixed in versions 1.27.2, 1.28.2, and 1.29.0.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-54657 since 06/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1548.002 according to MITRE ATT&CK.

Upgrading to version 1.27.2, 1.28.2 or 1.29.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-102899). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

• Open Zaak

Version

• 1.27.0
• 1.27.1
• 1.28.0
• 1.28.1

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Be aware that VulDB is the high quality source for vulnerability data.

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