Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-25833

53
FAUCET Score

CVE-2021-25833 is a critical file extension handling vulnerability affecting ONLYOFFICE DocumentServer versions 4.2.0.71 through 5.6.0.21. An unauthenticated remote attacker can exploit this flaw by manipulating request data to overwrite arbitrary files, ultimately leading to remote code execution. This vulnerability carries a CVSS score of 9.8 (Critical) due to its network-based attack vector, low complexity, and complete compromise of confidentiality, integrity, and availability. Despite its severity, there is currently no public exploit code available, nor is there evidence of active exploitation or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.2.0.71, <= 5.6.0.21CPE 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
43.53%
Probability of exploitation in next 30 days
EPSS Percentile
98.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.4353 is in the 96th percentile among its peer group of 36,862 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

Vendor Patches (1)

github_advisoryvendor investigatingvia nvd_reference
View patch

References

github.com / merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25833
ExploitThird Party Advisory
github.com / ONLYOFFICE/DocumentServer
ProductVendor Advisory
github.com / ONLYOFFICE/server
Product
github.com / ONLYOFFICE/server/blob/v5.6.0.21/DocService/sources/converterservice.js
Third Party Advisory
github.com / ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js
Third Party Advisory
github.com / ONLYOFFICE/server/blob/v5.6.0.21/FileConverter/sources/converter.js
Third Party Advisory