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PYSEC-2026-3830

HighCVSS 7.2 / 10

Published Sep 10, 2026·Last modified Sep 10, 2026

Affected Components(1)

document-merge-service

< 9.1.0

Description

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

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Risk Scores

Base Score

7.2

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence

6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS

N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Related Vulnerabilities

CVE-2026-53964
Alias

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High severity

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