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.
CVE-2026-53964
HIGHPre-NVD 7.27.2—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (40th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.2Exploit: None knownExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 7.2
- EG Score
- 7.2HIGHmedium confidence
- EG Risk
- 37EG Risk 37/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity72% × 45%Exploitation0% × 40%Automatability30% × 15%CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.5%
- EPSS %ILE
- 40th
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
August 19, 2026
Last Modified
October 2, 2026
Advisory Details (2)
Auto-updated Oct 1, 2026Patch available. Sources: github_release, github.
github Patch Available
RCE via SSTI (xlsx tempaltes) · Advisory · adfinis/document-merge-service · GitHub
https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pcgithub_release Patch Available
v9.1.0
Patch available: adfinis/document-merge-service v9.1.0
https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0Vendor Advisories for CVE-2026-53964(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| document-merge-service | 5.2.0 ... 9.0.0 (32 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 8× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-10-05 09:32 UTCEG score recompute
- 2026-10-04 23:22 UTCEPSS rescore
- 2026-10-03 19:24 UTCEG score recompute
- 2026-10-03 14:26 UTCEPSS rescore
- 2026-10-02 18:51 UTCEG score recompute
- 2026-10-02 17:56 UTCEPSS rescore
- 2026-10-01 20:29 UTCEG score recompute
- 2026-09-28 21:42 UTCEG score recompute
- 2026-08-19 19:42 UTCEG score recompute
Related CVEs(same product + same CWE)
Frequently asked(5)
What is CVE-2026-53964?
CVE-2026-53964 is a high vulnerability published on August 19, 2026. 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…
When was CVE-2026-53964 disclosed?
CVE-2026-53964 was first published on August 19, 2026, with the most recent update on October 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53964 actively exploited?
CVE-2026-53964 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (40th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-53964?
CVE-2026-53964 has a CVSS base score of 7.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-53964?
A fix for CVE-2026-53964 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-53964 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-53964
Is Your Infrastructure Affected by CVE-2026-53964?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.