CVE-2026-53964

Summary

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

Severity

high

CVSS

7.2

EPSS

0.5% (p42)

CWE

CWE-1336

Also known as

GHSA-w47q-945m-q9pc

Published

2026-08-19

Updated

2026-08-19

Advisory 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

References

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

Related advisories

• CVE-2026-62681 — critical · npm/orval
• CVE-2026-62682 — critical · npm/orval
• CVE-2026-72717 — critical · npm/orval
• CVE-2026-71869 — critical · npm/orval
• CVE-2026-71871 — critical · npm/orval
• CVE-2026-71868 — critical · npm/orval
• CVE-2026-72716 — critical · npm/orval
• CVE-2026-55559 — critical · Maven/org.yamcs:yamcs-core

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