{"id":"CVE-2021-3199","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-3199","generatedAt":"2026-10-27T20:20:14.702Z","title":"ONLYOFFICE Docs Server Path Traversal Vulnerability","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.","published":"2021-01-26T18:16:29.000Z","lastModified":"2026-10-09T14:20:47.000Z","status":"Analyzed","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-22"],"affected":["onlyoffice/document server"],"epss":{"score":0.30244,"percentile":0.98209,"date":"2026-10-26","history":[{"date":"2026-10-09","score":0.14548,"percentile":0.96569},{"date":"2026-10-10","score":0.19352,"percentile":0.97295},{"date":"2026-10-25","score":0.30244,"percentile":0.98208}]},"kev":{"listed":true,"dateAdded":"2026-10-08","dueDate":"2026-10-11","knownRansomwareCampaignUse":"Unknown","notes":"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.\nThis vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2021-3199"},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"Known to be exploited in the wild (CISA KEV, CISA remediation deadline 11 October 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise."},"changes":[{"kind":"epss","label":"EPSS jump","at":"2026-10-25T00:00:00.000Z","detail":{"to":0.30244,"from":0.20136,"percentile":0.98208},"summary":"EPSS moved from 20.1% to 30.2% probability of exploitation in the next thirty days."},{"kind":"epss","label":"EPSS jump","at":"2026-10-09T00:00:00.000Z","detail":{"to":0.14548,"from":0.08215,"percentile":0.96569},"summary":"EPSS moved from 8.2% to 14.5% probability of exploitation in the next thirty days."},{"kind":"kev","label":"Added to KEV","at":"2026-10-08T00:00:00.000Z","detail":{"name":"ONLYOFFICE Docs Server Path Traversal Vulnerability","vendor":"ONLYOFFICE","dueDate":"2026-10-11","product":"Docs","ransomware":"Unknown"},"summary":"Added to CISA KEV — known to be exploited; federal remediation due 2026-10-11."}],"references":[{"url":"https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563","tags":["Release Notes","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563","tags":["Release Notes","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3199","tags":["US Government Resource"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-3199","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}