What’s Vulnerable › Vulnerabilities

CVE-2026-53964: Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)

• Severity: high (CVSS 7.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-01 · updated 2026-10-02
• Weakness: CWE-1336

Description

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

References

• https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0
• https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc

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