CVE-2020-35685

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    CVE-2020-35685

    Published: 19 Aug 2021Last Modified: 10 Mar 2026

    Summary:

    Details: An issue was discovered in HCC Nichestack 3.0. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)

    References: https://www.hcc-embedded.com, , https://www.kb.cert.org/vuls/id/608209, https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf, https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: N/A

    Events:

    Introduced- None
    Fixed -None

    Affected versions

    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-2020-35685 | CVE-DB