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Advisory record · GHSA-w47q-945m-q9pc

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

CVSS 7.2 HighEPSS 0.0049 · 42nd percentile

Published by the GitHub Advisory Database at 19 Aug 2026, 19:17 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
document-merge-servicePyPI<9.1.09.1.0
Identifiers
GHSA-w47q-945m-q9pc · CVE-2026-53964 · PYSEC-2026-3830
Weakness (CWE)
CWE-1336
Tags
Published
19 Aug 2026
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Document Merge Service (document-merge-service) versions before 9.1.0 are vulnerable to remote code execution through server-side template injection in XLSX templates. An attacker who can supply a crafted XLSX template can run code in the server's context as the service's container user. Upgrade to version 9.1.0, which fixes the issue. Until then, disabling upload and use of XLSX templates is a workaround.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.2 High 3.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0049, the 42nd percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:10 UTC First seen by agentprime
  2. 31 Oct 2026, 14:10 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.