CVE-2021-3199

Name: CVE-2021-3199
Creator: NVD / NIST
Published: 2021-01-26T18:16:28.507+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 8.21%

Last modified Jun 17, 2026

CVE-2021-3199 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 8.21% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

8.21%

94.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-22

Affected Software

Vendor	Product	Versions
Onlyoffice	Document Server	< 5.6.3

References

https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563Release Notes, Third Party Advisory
https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.pyExploit, Third Party Advisory
https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.pyExploit, Third Party Advisory
https://github.com/ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md#563Release Notes, Third Party Advisory
https://github.com/moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.pyExploit, Third Party Advisory
https://github.com/nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.pyExploit, Third Party Advisory

Timeline

Published: Jan 26, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3199?

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.

How severe is CVE-2021-3199?

CVE-2021-3199 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 8.21% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3199?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-3199?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST