# CVE-2021-3199: ONLYOFFICE Docs Server path traversal in image upload

Source: https://junglewise.ai/threats/cve-2021-3199-onlyoffice-docs-server-path-traversal-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-08. Updated: 2026-10-08  
License: CC BY 4.0 with a link back

CVE-2021-3199 · Severity: critical · Exploited in the wild · Published 2026-10-08

ONLYOFFICE Docs is a collaborative document editing server. A path traversal vulnerability in the image upload feature allows attackers to write files to arbitrary locations on the server, potentially leading to remote code execution and complete compromise of the system.

Vendors: [ONLYOFFICE](https://junglewise.ai/threats/vendors/onlyoffice).

## Quick answers

**Is CVE-2021-3199 exploited in the wild?** Yes. CVE-2021-3199 is known to be exploited in the wild, first recorded on 8 October 2026. Treat it as urgent.

**How severe is CVE-2021-3199?** Critical severity, published 8 October 2026.

**Which products and versions are affected?** ONLYOFFICE Docs Server.

**Is there a fix for CVE-2021-3199?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-3199 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2021-3199?** Check whether you run ONLYOFFICE Docs or ONLYOFFICE Docs Server. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A path traversal vulnerability exists in ONLYOFFICE Docs' image upload functionality when JWT authentication is enabled, exploitable via /.. sequences in the upload parameter. The flaw allows an authenticated attacker to traverse the file system and write files outside the intended upload directory, leading to remote code execution. This vulnerability has been exploited in the wild.

## Affected products

- ONLYOFFICE Docs Server

## Timeline

- 2021: disclosed: CVE-2021-3199
- exploited: Confirmed exploitation in the wild