---
id: CVE-2026-53964
title: >-
  Document Merge Service is a document template merge service providing an API
  to manage templates and merge them with given data
summary: >-
  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 u…
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-1336
vendor: adfinis
product: document-merge-service
affected:
  - document-merge-service < 9.1.0
patched:
  - document-merge-service 9.1.0
published: '2026-10-01'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T18:47:49.947'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53964'
references:
  - url: 'https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc
    label: security-advisories@github.com
  - url: 'https://github.com/adfinis/document-merge-service'
  - url: 'https://pypi.org/project/document-merge-service'
  - url: 'https://github.com/advisories/GHSA-w47q-945m-q9pc'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53964'
tags:
  - nvd
  - cve.org
  - osv
  - pip
  - ghsa
epss: 0.00493
epssPercentile: 0.42113
aliases:
  - GHSA-w47q-945m-q9pc
  - PYSEC-2026-3830
ecosystem: pip
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-01T20:12:41.561346Z'
ingestedAt: '2026-08-19T19:44:03.129Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-53964)

Affected packages:

- `document-merge-service < 9.1.0`

Patched in:

- `document-merge-service 9.1.0`

Source: https://osv.dev/vulnerability/GHSA-w47q-945m-q9pc