CVE-2021-3199
onlyoffice document server
Published 26 Jan 2021 · updated 8 Oct 2026 · Modified
Exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on 8 Oct 2026, with a remediation deadline of 11 Oct 2026 for US federal agencies.
Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Description
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.
References
- github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563 · Release Notes, Third Party Advisory
- github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py · Exploit, Third Party Advisory
- github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py · Exploit, Third Party Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3199