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CVE-2021-3199

33
FAUCET Score

CVE-2021-3199 is a critical directory traversal vulnerability affecting ONLYOFFICE Document Server versions prior to 5.6.3. When JSON Web Tokens (JWT) are enabled, an unauthenticated attacker can achieve remote code execution by manipulating image upload parameters with a "../" sequence. This vulnerability carries a CVSS score of 9.8, indicating a severe risk with high impact on confidentiality, integrity, and availability, and can be exploited remotely with low attack complexity. While no public exploit code or active exploitation has been observed, and community discussion is minimal, the high FAUCET Risk Score suggests its potential for significant compromise.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.6.3CPE matchmatch criteria
cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
8.21%
Probability of exploitation in next 30 days
EPSS Percentile
94.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0822 is in the 90th percentile among its peer group of 36,833 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Remediation records are not available for this CVE.

References

github.com / moehw/poc_exploits/tree/master/CVE-2021-3199/poc_uploadImageFile.py
ExploitThird Party Advisory
github.com / nola-milkin/poc_exploits/blob/master/CVE-2021-3199/poc_uploadImageFile.py
ExploitThird Party Advisory
github.com / ONLYOFFICE/DocumentServer/blob/903fe5ab7a275bd69c3c3346af2d21cf87ebeabf/CHANGELOG.md
Release NotesThird Party Advisory