{"id":"CVE-2026-53964","aliases":["GHSA-w47q-945m-q9pc","PYSEC-2026-3830"],"url":"https://o3.security/vulnerability/CVE-2026-53964","summary":"Document Merge Service vulnerable to RCE via SSTI (xlsx tempaltes)","details":"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.","published":"2026-10-01T19:55:07.504Z","modified":"2026-10-04T02:30:38.457824741Z","cvss":{"score":7.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"PyPI","name":"document-merge-service","fixedVersion":"9.1.0"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/adfinis/document-merge-service/releases/tag/v9.1.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53964.json"},{"type":"ADVISORY","url":"https://github.com/adfinis/document-merge-service/security/advisories/GHSA-w47q-945m-q9pc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53964"},{"type":"PACKAGE","url":"https://github.com/adfinis/document-merge-service"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-04T02:30:38.457824741Z"}}