Open Zaak up to 1.27.1/1.28.1 documenten tasks.py _import_document_row bestandspad path traversal

Summaryinfo

A vulnerability labeled as problematic has been found in Open Zaak up to 1.27.1/1.28.1. Affected by this issue is the function _import_document_row of the file src/openzaak/components/documenten/tasks.py of the component documenten. Executing a manipulation of the argument bestandspad can lead to path traversal. This vulnerability is tracked as CVE-2026-55836. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability has been found in Open Zaak up to 1.27.1/1.28.1 and classified as problematic. This vulnerability affects the function _import_document_row of the file src/openzaak/components/documenten/tasks.py of the component documenten. The manipulation of the argument bestandspad with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality. CVE summarizes:

Open Zaak is an open-source data and services layer for Dutch case-oriented working. From 1.13.0 until 1.27.2, 1.28.2, and 1.29.0, _import_document_row in src/openzaak/components/documenten/tasks.py uses the attacker-controlled bestandspad CSV field without ensuring that the resolved path remains under IMPORT_DOCUMENTEN_BASE_DIR. A client with an all-authorizations application token can supply an absolute or parent-traversal path to a file readable by the Celery service account. The worker copies that file into document storage, allowing its contents to be retrieved through the normal document download API and exposing server secrets or other private files. This issue is fixed in versions 1.27.2, 1.28.2, and 1.29.0.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-55836 since 06/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

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-2026-102900). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• Open Zaak

Version

• 1.27.0
• 1.27.1
• 1.28.0
• 1.28.1

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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