CVE-2021-25829

7.5 highEPSS 7.4%

High (7.5) in onlyoffice document server. EPSS 7.4% chance of exploitation in the next 30 days.

An improper binary stream data handling issue was found in the [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3. Using this bug, an attacker is able to produce a denial of service attack that can eventually shut down the target server.

Severity

CVSS 3.1

7.5 high

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

EPSS: 7.4% chance of exploitation in the next 30 days; higher than 94% of CVEs (scores of 2026-10-31)
Published: 2021-03-01
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

onlyoffice:document_server

References

https://github.com/ONLYOFFICE/DocumentServer
https://github.com/ONLYOFFICE/core
https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Comments.h#L299
https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Core.h#L161
https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesMaster.h#L148

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