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Critical severity · published Mar 1, 2021
CVE-2021-25831
A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3
9.8
CVSS
11.5%
EPSS
No
On KEV
Description
A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.0.0-9-v5.6.3. An attacker must request the conversion of the crafted file from PPTT into PPTX format. Using the chain of two other bugs related to improper string handling, a remote attacker can obtain remote code execution on DocumentServer.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)11.5% · higher than 96% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DS
Document Server · Onlyoffice
4.0.0-9 through 5.6.3 · source: NVD
Affected product
DS
Document Server
Onlyoffice
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-25831
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-25831
Product
https://github.com/ONLYOFFICE/DocumentServer
Product
https://github.com/ONLYOFFICE/core
Vendor Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1918
Vendor Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L241
Vendor Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/Fills/BlipFill.cpp#L328
Exploit
https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25831
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