CVE-2021-3199

ONLYOFFICE Docs Server Path Traversal Vulnerability

Exploited in attacks Critical 9.8 Attack chance: 30%

What it is

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.

CISA: 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.

What to do

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.

Deadline for US federal agencies: October 11, 2026

Added to the CISA list: October 8, 2026
Published: January 22, 2021
Severity: Critical 9.8 CVSS 3.1
Chance of attacks in the next 30 days (EPSS): 30% in the top 1.8% of all known vulnerabilities
Weakness: CWE-22
More details: NVD · CVE.org · CISA

All references (3)

Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.