High · CVSS 7.2CVE-2026-53964GHSA-W47Q-945M-Q9PC

Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)

Answer in brief

CVE-2026-53964 records a High severity (CVSS 7.2) vulnerability in Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes). The current sources do not mark it as known exploited. The current feed maps adfinis/document-merge-service (generic), document-merge-service (pip), document-merge-service (pypi). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 1, 2026Updated Oct 1, 2026Source checked Oct 1, 2026First seen by HOL Aug 19, 2026Material review Oct 1, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.2
Exploitation: Not marked as known exploited
Affected software: 3 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps adfinis/document-merge-service (generic), document-merge-service (pip), document-merge-service (pypi). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
adfinis/document-merge-servicegeneric	<9.1.0	9.1.0
document-merge-servicepip	<9.1.0	9.1.0
document-merge-servicepypi	>=0 <9.1.0	9.1.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for adfinis/document-merge-service, document-merge-service, document-merge-service.
Review the reported fix. Update adfinis/document-merge-service to 9.1.0; document-merge-service to 9.1.0; document-merge-service to 9.1.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 1, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 19, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.