CVE entry · CVE-2021-3199
CVE-2021-3199: ONLYOFFICE Docs Server Path Traversal Vulnerability
ONLYOFFICE Docs contains a path traversal vulnerability that can occur when JWT is used, via a /.. sequence in an image upload parameter and could allow for remote code execution.
- Actively exploited: added to CISA’s KEV catalog on October 8, 2026.
- Use by ransomware: not established so far.
- Remediation deadline for US federal agencies: October 11, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes ONLYOFFICE Docs, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.