# CVE-2021-3199

Directory traversal with remote code execution can occur in /upload in ONLYOFFICE Document Server before 5.6.3, when JWT is used, via a /.. sequence in an image upload parameter.

- Page: https://www.vulneraibility.com/cve/CVE-2021-3199
- CVSS: 9.8
- Known exploited: yes, in CISA KEV since 2026-10-08; CISA due date 2026-10-11
- EPSS: 30.24%
- CISA SSVC: exploitation active, automatable yes, technical impact total (assessed 2026-10-08)
- Weakness: CWE-22
- Published: 2021-01-26

## Affected

- onlyoffice:document_server

## References

- [other] https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563
- [other] https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py
- [other] https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py
- [other] https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3199

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.