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    CVE-2026-21878

    BACnet Stack is a BACnet open source protocol stack C library for embedded systems. Prior to 1.5.0.rc3, a vulnerability has been discovered in BACnet Stack's file writing functionality where there is no validation of user-provided file paths, allowing attackers to write files to arbitrary directories. This affects apps/readfile/main.c and ports/posix/bacfile-posix.c. This vulnerability is fixed in 1.5.0.rc3.

    Published:Feb 13, 2026
    Last Modified:Apr 17, 2026
    EPS:Feb 13, 2026
    EPSS Score:0.00101
    CVSS Score:7.5

    Affected Products

    Vendor
    Bacnetstack
    Product
    Bacnet Stack

    Exploits

    https://github.com/bacnet-stack/bacnet-stack/security/advisories/GHSA-p8rx-c26w-545j

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    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