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.

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This report contains official claims from a government or institutional source and may not be independently verified.

Threat HighOfficial ClaimGovernmentConf ConfirmedUnited States · North AmericaPublishedCISA

Original publisher

CISA

Original source URL

https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563

Source country

United States

Reporting region

North America

Language

Institution

CISA

Published (UTC)

Oct 8, 2026, 12:00 AM

Ingested (UTC)

Oct 16, 2026, 3:02 PM

Verification

Official Claim

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CVE-2021-3199: ONLYOFFICE Docs Server Path Traversal Vulnerability
Vendor/project: ONLYOFFICE
Product: Docs
Date added to KEV: 2026-10-08
Due date: 2026-10-11
Known ransomware use: Unknown
CWEs: CWE-22
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.

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.

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
CISA KEV catalog entry for CVE-2021-3199
Original source: https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563

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