MediumCVE-2025-41739

    CODESYS Control - Linux/QNX SysSocket flaw (CVE-2025-41739)

    Published Sources: BSI, CVE.org

    What is affected, what to do

    An unauthenticated remote attacker, who beats a race condition, can exploit a flaw in the communication servers of the CODESYS Control runtime system on Linux and QNX to trigger an out-of-bounds read via crafted socket communication, potentially causing a denial of service.

    Update CODESYS PLCHandler to version 3.5.21.40, CODESYS Remote Target Visu to version 3.5.21.40, CODESYS Runtime Toolkit to version 3.5.21.40.

    Affected
    • CODESYS PLCHandler lt 3.5.21.0..3.5.21.40
    • CODESYS Remote Target Visu lt 3.5.21.0..3.5.21.40
    • CODESYS Runtime Toolkit lt 3.5.21.0..3.5.21.40
    • CODESYS Control for BeagleBone SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for emPC-A/iMX6 SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for IOT2000 SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for Linux ARM SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for Linux SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for PFC100 SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for PFC200 SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for PLCnext SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for Raspberry Pi SL lt 4.15.0.0..4.19.0.0
    • CODESYS Control for WAGO Touch Panels 600 SL lt 4.15.0.0..4.19.0.0
    • CODESYS Edge Gateway for Linux lt 4.15.0.0..4.19.0.0
    • CODESYS TargetVisu for Linux SL lt 4.15.0.0..4.19.0.0
    • CODESYS Virtual Control SL lt 4.15.0.0..4.19.0.0
    Fixed in
    • CODESYS PLCHandler 3.5.21.40
    • CODESYS Remote Target Visu 3.5.21.40
    • CODESYS Runtime Toolkit 3.5.21.40
    • CODESYS Control for BeagleBone SL 4.19.0.0
    • CODESYS Control for emPC-A/iMX6 SL 4.19.0.0
    • CODESYS Control for IOT2000 SL 4.19.0.0
    • CODESYS Control for Linux ARM SL 4.19.0.0
    • CODESYS Control for Linux SL 4.19.0.0
    • CODESYS Control for PFC100 SL 4.19.0.0
    • CODESYS Control for PFC200 SL 4.19.0.0
    • CODESYS Control for PLCnext SL 4.19.0.0
    • CODESYS Control for Raspberry Pi SL 4.19.0.0
    • CODESYS Control for WAGO Touch Panels 600 SL 4.19.0.0
    • CODESYS Edge Gateway for Linux 4.19.0.0
    • CODESYS TargetVisu for Linux SL 4.19.0.0
    • CODESYS Virtual Control SL 4.19.0.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    5.9

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    5.9

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: BSI, CVE.org

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 28.2

    Show all metrics
    Severity
    Medium
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    48.27 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    5.9 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    5.9
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.4 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    28.2
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 1 December 2025
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-125

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    An unauthenticated remote attacker, who beats a race condition, can exploit a flaw in the communication servers of the CODESYS Control runtime system on Linux and QNX to trigger an out-of-bounds read via crafted socket communication, potentially causing a denial of service.

    Source: BSI CSAF, BSI WID Portal, cvelistv5, NVD (NIST)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    CODESYSCODESYS Control for BeagleBone SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for emPC-A/iMX6 SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for IOT2000 SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for Linux ARM SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for Linux SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for PFC100 SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for PFC200 SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for PLCnext SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for Raspberry Pi SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Control for WAGO Touch Panels 600 SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Edge Gateway for Linux
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS PLCHandler
    • 3.5.21.0 – < 3.5.21.40
    • 3.5.21.40
    CODESYSCODESYS Remote Target Visu
    • 3.5.21.0 – < 3.5.21.40
    • 3.5.21.40
    CODESYSCODESYS Runtime Toolkit
    • 3.5.21.0 – < 3.5.21.40
    • 3.5.21.40
    CODESYSCODESYS TargetVisu for Linux SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    CODESYSCODESYS Virtual Control SL
    • 4.15.0.0 – < 4.19.0.0
    • 4.19.0.0
    ABBAC-500
    • < 3.9.1
    • 3.9.1
    CODESYSCODESYS Control
    • < 4.19.0.0
    • 4.19.0.0

    Vendors and products

    Weakness classes (CWE)

    • CWE-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    References & sources

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