CVE-2021-25831

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    CVE-2021-25831

    Published: 1 Mar 2021Last Modified: 7 Aug 2026

    Summary:

    Details: 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.

    References: https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L1918, https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/Editor/BinaryFileReaderWriter.cpp#L241, https://github.com/ONLYOFFICE/core/blob/v5.6.4.13/ASCOfficePPTXFile/PPTXFormat/Logic/Fills/BlipFill.cpp#L328, https://github.com/ONLYOFFICE/DocumentServer, https://github.com/ONLYOFFICE/core, https://github.com/merrychap/poc_exploits/tree/master/ONLYOFFICE/CVE-2021-25831

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 1e2a61f6f4321e2571474068595dfe23a657cbdf
    Fixed -None

    Affected versions

    ONLYOFFICE-DocumentServer-5.6.3
    ONLYOFFICE-DocumentServer-5.6.2
    ONLYOFFICE-DocumentServer-5.6.1
    ONLYOFFICE-DocumentServer-5.6.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2021-25831 | CVE-DB