CVE-2026-53964: Adfinis Document-Merge-Service

High severity, CVSS 7.2. EPSS: 0.5% chance of exploitation in the next 30 days.

Document Merge Service is a document template merge service providing an API to manage templates and merge them with given data. Prior to version 9.1.0, a remote code execution (RCE) via server-side template injection (SSTI) allows for user supplied code to be executed in the server's context where it is executed as the document-merge-server user with the UID 901 thus giving an attacker considerable control over the container. The vulnerability is limited to XLSX templates, were the xltpl library uses a npn-sandboxed Jinja environment for the processing of the template. This issue has been patched in version 9.1.0.

Affected products

• Adfinis Document-Merge-Service: before 9.1.0 (fixed in 9.1.0)

Published 2026-10-01. Last modified 2026-10-02.