{"cve":{"cve_id":"CVE-2021-3199","is_kev":true,"kev_date_added":"2026-10-08","kev_vendor_project":"ONLYOFFICE","kev_product":"Docs","kev_vulnerability_name":"ONLYOFFICE Docs Server Path Traversal Vulnerability","kev_short_description":"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.","kev_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.","kev_due_date":"2026-10-11","kev_known_ransomware":false,"kev_notes":"This 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","kev_cwes":["CWE-22"],"epss_score":0.19352,"epss_percentile":0.97319,"epss_as_of":"2026-10-15","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_at":"2021-01-22T02:41:34Z","last_modified_at":"2026-10-09T14:20:47.350000Z","cvss_v3_score":9.8,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_v3_severity":"CRITICAL","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-22"],"nvd_references":["https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563","https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py","https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py"],"vuln_status":"Analyzed","trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-10-10T21:36:59.224259Z"},"effective_severity":"CRITICAL","badges":["kev"],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"H","value_label":"High"},{"metric":"I","name":"Integrity","value":"H","value_label":"High"},{"metric":"A","name":"Availability","value":"H","value_label":"High"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"onlyoffice","vendor_name":"ONLYOFFICE","product_slug":"document-server","product_name":"Document Server","version_start":null,"version_start_inclusive":null,"version_end":"5.6.3","version_end_inclusive":false,"cpe23_uri":"cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:*"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563","source_type":"MISC","tags":[]},{"url":"https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py","source_type":"MISC","tags":[]},{"url":"https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py","source_type":"MISC","tags":[]}],"timeline":[{"type":"published","at":"2021-01-22T02:41:34Z","label":"CVE published","source":null},{"type":"cisa_reported","at":"2026-10-08T00:00:00Z","label":"Added to CISA KEV catalog","source":"kev"},{"type":"cvss_changed","at":"2026-10-08T19:37:29.207977Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-10-08T19:37:29.207977Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-10-08T19:37:29.207977Z","label":"CVSS score revised","source":"cvelistv5"}]}