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CVE-2021-25829

27
FAUCET Score

CVE-2021-25829 describes an improper binary stream data handling vulnerability in ONLYOFFICE DocumentServer versions 4.0.0-9 through 5.6.3. This flaw allows an unauthenticated attacker to remotely trigger a denial of service (DoS) condition, potentially shutting down the affected server. While rated with a CVSS score of 7.5 (High), indicating a significant impact on availability, there is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.0.0-9, <= 5.6.3CPE matchmatch criteria
cpe:2.3:a:onlyoffice:document_server:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
7.45%
Probability of exploitation in next 30 days
EPSS Percentile
93.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0745 is in the 90th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 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-2021-25829
ExploitThird Party Advisory
github.com / ONLYOFFICE/core
ProductVendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Comments.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Core.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesMaster.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesSlide.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Presentation.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Theme.h
Vendor Advisory
github.com / ONLYOFFICE/core/blob/v5.6.4.10/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp
Vendor Advisory
github.com / ONLYOFFICE/DocumentServer
Product