Critical severity · published Jan 22, 2021
CVE-2021-3199
ONLYOFFICE Docs Server Path Traversal Vulnerability
In wildKEV
9.8
CVSS
30.2%
EPSS
Yes
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)30.2% · higher than 98% of CVEs
Exploited in the wildYes
CISA KEVListed Oct 8, 2026
Federal remediation dueOct 11, 2026
Ransomware campaign useNot known
Affected products
Which versions
DS
Document Server · Onlyoffice
before 5.6.3 · source: NVD
DO
Docs · ONLYOFFICE
All versions, or not specified · source: KEV
In the news
AdvisoryHigh
Chinese Government-linked Cyber Threat Actors Combine Automated and Hands-on Hacking Tools to Steal Sensitive Data
Advisory at a Glance  Title  Chinese Government-linked Cyber Threat Actors Combine Automated and Hands-on Hacking Tools to Steal Sensitive Data  Original Publication  October 8, 2026   Executive Summary  Chinese government-linked cyber threat actors, enabled by the Integrity Technology Group, are combining automated scanning tools, large-scale botnets, and hands-on exploitation techniques to target and steal sensitive data from organizations worldwide, including US critical infrastructure sectors. These actors exploit vulnerabilities by using scanning tools, cross-site scripting attacks, and password spraying on Microsoft Exchange servers, while establishing persistence through VPN software and exfiltrating emails and credentials using scripts. To help mitigate against this activity, organizations should prioritize disabling unused services and ports, sanitizing web application inputs to prevent injection attacks, implementing multifactor authentication for all services, and applying timely patches to reduce risks of compromise.  Affected Products  CVE-2014-6278   CVE-2015-3306   CVE-2015-5477   CVE-2016-3081   CVE-2019-11510   CVE-2021-22205   CVE-2021-3199   CVE-2023-22894   Key Actions  ...
Oct 8, 2026·CISA Advisories
VulnerabilityCritical
[CISA KEV] CVE-2021-3199: ONLYOFFICE Docs - 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.
Oct 8, 2026·CISA KEV
Affected product
DS
Document Server
Onlyoffice
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