CriticalCVE-2021-25669

    Siemens SCALANCE: Stack-based Buffer Overflow (CVE-2021-25669)

    Published Sources: CVE.org

    What is affected, what to do

    A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT PRO (All versions < 5.5.1), SCALANCE X202-2 IRT (All versions < 5.5.1), SCALANCE X202-2P IRT (incl. SIPLUS NET variant) (All versions < 5.5.1), SCALANCE X202-2P IRT PRO (All versions < 5.5.1), SCALANCE X204 IRT (All versions < 5.5.1), SCALANCE X204 IRT PRO (All versions < 5.5.1), SCALANCE X204-2 (incl.

    The available sources name no fixed version. Check the vendor guidance in the references below.

    Affected
    • Siemens SCALANCE X200-4P IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X201-3P IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X201-3P IRT PRO eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X202-2 IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X202-2P IRT (incl. SIPLUS NET variant) eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X202-2P IRT PRO eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X204 IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X204 IRT PRO eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE X204-2 (incl. SIPLUS NET variant) eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X204-2FM eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X204-2LD (incl. SIPLUS NET variant) eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X204-2LD TS eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X204-2TS eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X206-1 eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X206-1LD eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X208 (incl. SIPLUS NET variant) eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X208PRO eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X212-2 (incl. SIPLUS NET variant) eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X212-2LD eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X216 eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE X224 eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE XF201-3P IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE XF202-2P IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE XF204 eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE XF204 IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE XF204-2 (incl. SIPLUS NET variant) eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE XF204-2BA IRT eq All versions < 5.5.1..All versions < 5.5.1
    • Siemens SCALANCE XF206-1 eq All versions < V5.2.5..All versions < V5.2.5
    • Siemens SCALANCE XF208 eq All versions < V5.2.5..All versions < V5.2.5

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    Metrics

    9.8

    Priority

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

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org

    2.1 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 82.0

    Show all metrics
    Severity
    Critical
    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
    102.73 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
    9.8 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
    9.8
    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
    2.1 %
    Moderate — model estimates 1-10% 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
    82.0
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    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
    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-121

    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
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    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

    A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT PRO (All versions < 5.5.1), SCALANCE X202-2 IRT (All versions < 5.5.1), SCALANCE X202-2P IRT (incl. SIPLUS NET variant) (All versions < 5.5.1), SCALANCE X202-2P IRT PRO (All versions < 5.5.1), SCALANCE X204 IRT (All versions < 5.5.1), SCALANCE X204 IRT PRO (All versions < 5.5.1), SCALANCE X204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2FM (All versions < V5.2.5), SCALANCE X204-2LD (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2LD TS (All versions < V5.2.5), SCALANCE X204-2TS (All versions < V5.2.5), SCALANCE X206-1 (All versions < V5.2.5), SCALANCE X206-1LD (All versions < V5.2.5), SCALANCE X208 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X208PRO (All versions < V5.2.5), SCALANCE X212-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X212-2LD (All versions < V5.2.5), SCALANCE X216 (All versions < V5.2.5), SCALANCE X224 (All versions < V5.2.5), SCALANCE XF201-3P IRT (All versions < 5.5.1), SCALANCE XF202-2P IRT (All versions < 5.5.1), SCALANCE XF204 (All versions < V5.2.5), SCALANCE XF204 IRT (All versions < 5.5.1), SCALANCE XF204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE XF204-2BA IRT (All versions < 5.5.1), SCALANCE XF206-1 (All versions < V5.2.5), SCALANCE XF208 (All versions < V5.2.5). Incorrect processing of POST requests in the web server may write out of bounds in stack. An attacker might leverage this to denial-of-service of the device or remote code execution.

    Source: NVD (NIST), cvelistv5

    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
    SiemensSCALANCE X200-4P IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X201-3P IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X201-3P IRT PRO
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X202-2 IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X202-2P IRT (incl. SIPLUS NET variant)
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X202-2P IRT PRO
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X204 IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X204 IRT PRO
    • All versions < 5.5.1
    • —
    SiemensSCALANCE X204-2 (incl. SIPLUS NET variant)
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X204-2FM
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X204-2LD (incl. SIPLUS NET variant)
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X204-2LD TS
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X204-2TS
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X206-1
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X206-1LD
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X208 (incl. SIPLUS NET variant)
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X208PRO
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X212-2 (incl. SIPLUS NET variant)
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X212-2LD
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X216
    • All versions < V5.2.5
    • —
    SiemensSCALANCE X224
    • All versions < V5.2.5
    • —
    SiemensSCALANCE XF201-3P IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE XF202-2P IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE XF204
    • All versions < V5.2.5
    • —
    SiemensSCALANCE XF204 IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE XF204-2 (incl. SIPLUS NET variant)
    • All versions < V5.2.5
    • —
    SiemensSCALANCE XF204-2BA IRT
    • All versions < 5.5.1
    • —
    SiemensSCALANCE XF206-1
    • All versions < V5.2.5
    • —
    SiemensSCALANCE XF208
    • All versions < V5.2.5
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othersiemensscalance_x200-4p_irt_firmware—
    Othersiemensscalance_x201-3p_irt_firmware—
    Othersiemensscalance_x201-3p_irt_pro_firmware—
    Othersiemensscalance_x202-2_irt_firmware—
    Othersiemensscalance_x202-2p_irt_firmware—
    Othersiemensscalance_x202-2p_irt_pro_firmware—
    Othersiemensscalance_x204-2_firmware—
    Othersiemensscalance_x204-2fm_firmware—
    Othersiemensscalance_x204-2ld_firmware—
    Othersiemensscalance_x204-2ld_ts_firmware—
    Othersiemensscalance_x204-2ts_firmware—
    Othersiemensscalance_x204_irt_firmware—
    Othersiemensscalance_x204_irt_pro_firmware—
    Othersiemensscalance_x206-1_firmware—
    Othersiemensscalance_x206-1ld_firmware—
    Othersiemensscalance_x208_firmware—
    Othersiemensscalance_x208pro_firmware—
    Othersiemensscalance_x212-2_firmware—
    Othersiemensscalance_x212-2ld_firmware—
    Othersiemensscalance_x216_firmware—
    Othersiemensscalance_x224_firmware—
    Othersiemensscalance_xf201-3p_irt_firmware—
    Othersiemensscalance_xf202-2p_irt_firmware—
    Othersiemensscalance_xf204-2_firmware—

    Weakness classes (CWE)

    • CWE-121Stack-based Buffer Overflow

      Variant

      A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

      Entry at MITRE CWE-121

    References & sources

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    Badge preview for CVE-2021-25669
    <a href="https://intel.neosec.eu/en/cve/CVE-2021-25669"><img src="https://intel.neosec.eu/badge/cve/CVE-2021-25669.svg?lang=en" alt="CVE-2021-25669 – NEOSEC Intel" height="20"></a>