{"id":"CVE-2026-53964","aliases":["GHSA-w47q-945m-q9pc","PYSEC-2026-3830"],"title":"Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)","summary":"Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)","severity":"high","cvss":7.2,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","vendor":"document-merge-service","product":"document-merge-service","ecosystem":"pip","affected":["document-merge-service < 9.1.0"],"patched":["document-merge-service 9.1.0"],"published":"2026-08-19","updated":"2026-09-10","sourceUpdated":"2026-09-10T12:25:55.406064842Z","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-w47q-945m-q9pc","references":[{"url":"https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc"},{"url":"https://github.com/adfinis/document-merge-service"},{"url":"https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0"},{"url":"https://pypi.org/project/document-merge-service"},{"url":"https://github.com/advisories/GHSA-w47q-945m-q9pc"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53964"}],"tags":["osv","pip","ghsa"],"cwe":["CWE-1336"],"ingestedAt":"2026-08-19T19:44:03.129Z","slug":"CVE-2026-53964","body":"## Overview\n\n### Impact\nA 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. \n\n### Patches\nIt has been patched in [v9.1.0](https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0)\n\n### Workarounds\nDisable the upload/usage of XLSX templates.\n\n### References\nAre there any links users can visit to find out more?\n\nhttps://book.hacktricks.xyz/pentesting-web/ssti-server-side-template-injection/jinja2-ssti\n\n## Affected packages\n\n- `document-merge-service < 9.1.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `document-merge-service 9.1.0`","depth":"twilight","depthScore":40,"depthScoreParts":{"impact":39.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}