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Critical severity · published Mar 1, 2021
CVE-2021-25830
A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.2.0.236-v5.6.4.13
9.8
CVSS
11.8%
EPSS
No
On KEV
Description
A file extension handling issue was found in [core] module of ONLYOFFICE DocumentServer v4.2.0.236-v5.6.4.13. An attacker must request the conversion of the crafted file from DOCT into DOCX format. Using the chain of two other bugs related to improper string handling, an attacker can achieve 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)11.8% · 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
4.2.0.236 through 5.6.4.13 · source: NVD
Affected product
DS
Document Server
Onlyoffice
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-25830
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-25830
Product
https://github.com/ONLYOFFICE/DocumentServer
Product
https://github.com/ONLYOFFICE/core
Third Party Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1918
Third Party Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L241
Third Party Advisory
https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/UniFill.cpp#L343
Exploit
https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25830
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