GHSA-W47Q-945M-Q9PC
Vulnerability from github – Published: 2026-08-19 19:17 – Updated: 2026-08-19 19:17
VLAI
Summary
Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)
Details
Impact
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.
Patches
It has been patched in v9.1.0
Workarounds
Disable the upload/usage of XLSX templates.
References
Are there any links users can visit to find out more?
https://book.hacktricks.xyz/pentesting-web/ssti-server-side-template-injection/jinja2-ssti
Severity
7.2 (High)
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "document-merge-service"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "9.1.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-53964"
],
"database_specific": {
"cwe_ids": [
"CWE-1336"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-19T19:17:19Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Impact\nA remote code execution (RCE) via server-side template injection (SSTI) allows for user supplied code to be executed in the server\u0027s 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. \n\n### Patches\nIt has been patched in [v9.1.0](https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0)\n\n### Workarounds\nDisable the upload/usage of XLSX templates.\n\n### References\nAre there any links users can visit to find out more?\n\nhttps://book.hacktricks.xyz/pentesting-web/ssti-server-side-template-injection/jinja2-ssti",
"id": "GHSA-w47q-945m-q9pc",
"modified": "2026-08-19T19:17:19Z",
"published": "2026-08-19T19:17:19Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc"
},
{
"type": "PACKAGE",
"url": "https://github.com/adfinis/document-merge-service"
},
{
"type": "WEB",
"url": "https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)"
}
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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