CVE-2026-53964 json
Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)
published 2mo ago modified last mo. also GHSA-w47q-945m-q9pc , PYSEC-2026-3830 , EUVD-2026-91047
- cvss
- 7.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 42%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi document-merge-service 9.1.0
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- last mo.
Exploit prediction
0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
| OSV | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 7.2 | CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | document-merge-service | <9.1.0 |
9.1.0 |
Affected products
- adfinis document-merge-service
Classification
- Weakness
-
- CWE-1336 Improper Neutralization of Special Elements Used in a Template Engine
References
-
github.com
/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc
web
-
github.com
/adfinis/document-merge-service/releases/tag/v9.1.0
web
-
github.com
/adfinis/document-merge-service
package
-
pypi.org
/project/document-merge-service
package
-
github.com
/advisories/GHSA-w47q-945m-q9pc
advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-53964
advisory
Sources
- CVE List CVE-2026-53964
- GitHub Advisory GHSA-w47q-945m-q9pc
- NVD CVE-2026-53964
- OSV PYSEC-2026-3830
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.