CVE-2021-25829
An improper binary stream data handling issue was found in the [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (7.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 7.45% probability · 94th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- onlyoffice/document server
- Source
- cve@mitre.org
EPSS 7.4% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/ONLYOFFICE/DocumentServerProduct
- https://github.com/ONLYOFFICE/coreProduct, Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Comments.h#L299Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Core.h#L161Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesMaster.h#L148Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesSlide.h#L141Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Presentation.h#L277Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Theme.h#L277Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.10/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1722Vendor Advisory
- https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25829Exploit, Third Party Advisory
- https://github.com/ONLYOFFICE/DocumentServerProduct
- https://github.com/ONLYOFFICE/coreProduct, Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Comments.h#L299Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Core.h#L161Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesMaster.h#L148Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/NotesSlide.h#L141Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Presentation.h#L277Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/c1e4a2ce33bdcfab29d670f5fdb10fc63cf5fd6a/ASCOfficePPTXFile/PPTXFormat/Theme.h#L277Vendor Advisory
- https://github.com/ONLYOFFICE/core/blob/v5.6.4.10/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1722Vendor Advisory
- https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25829Exploit, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.