MediumCVE-2021-44694

    Siemens SIMATIC Drive Controller CPU 1504D TF: Improper Validation of Specified Type of Input (CVE-2021-44694)

    Published Sources: Siemens ProductCERT, CVE.org

    What is affected, what to do

    Affected devices don't process correctly certain special crafted packets sent to port 102/tcp, which could allow an attacker to cause a denial of service in the device.

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

    Affected
    • Siemens SIMATIC Drive Controller CPU 1504D TF eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC Drive Controller CPU 1507D TF eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) eq All versions < V21.9.7..All versions < V21.9.7
    • Siemens SIMATIC S7-1200 CPU family (incl. SIPLUS variants) eq All versions < V4.6.0..All versions < V4.6.0
    • Siemens SIMATIC S7-1500 CPU 1510SP F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1510SP-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1511-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1511C-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1511F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1511T-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1511TF-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1512C-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1512SP F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1512SP-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1513-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1513F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1513R-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1515-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1515F-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1515R-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1515T-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1515TF-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1516-3 PN/DP eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1516F-3 PN/DP eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU 1516T-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1516TF-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1517-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1517F-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1517H-3 PN eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1517T-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1517TF-3 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518HF-4 PN eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518T-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU 1518TF-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIMATIC S7-1500 CPU S7-1518-4 PN/DP ODK eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 CPU S7-1518F-4 PN/DP ODK eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 ET 200pro eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIMATIC S7-1500 Software Controller V2 eq All versions < V21.9.7..All versions < V21.9.7
    • Siemens SIMATIC S7-PLCSIM Advanced eq All versions < V5.0..All versions < V5.0
    • Siemens SIPLUS ET 200SP CPU 1510SP F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1510SP F-1 PN RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1510SP-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1510SP-1 PN RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1512SP F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1512SP F-1 PN RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1512SP-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS ET 200SP CPU 1512SP-1 PN RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1511-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1511-1 PN T1 RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1511-1 PN TX RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1511F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1513-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1513F-1 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1515F-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1515F-2 PN RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1515F-2 PN T2 RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1515R-2 PN eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1515R-2 PN TX RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1516-3 PN/DP eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1516-3 PN/DP RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1516-3 PN/DP TX RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1516F-3 PN/DP eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1516F-3 PN/DP RAIL eq All versions < V2.9.7..All versions < V2.9.7
    • Siemens SIPLUS S7-1500 CPU 1517H-3 PN eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIPLUS S7-1500 CPU 1518F-4 PN/DP eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIPLUS S7-1500 CPU 1518HF-4 PN eq All versions < V3.0.1..All versions < V3.0.1
    • Siemens SIPLUS TIM 1531 IRC eq All versions < V2.3.6..All versions < V2.3.6
    • Siemens TIM 1531 IRC eq All versions < V2.3.6..All versions < V2.3.6

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

    Metrics

    5.5

    Priority

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

    Source: Vendor (CNA), CVSS v3

    5.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Siemens ProductCERT, CVE.org

    0.7 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 51.4

    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
    50.48 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
    5.5 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
    5.5
    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
    0.7 %
    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
    51.4
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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 18 April 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-1287

    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

    Affected devices don't process correctly certain special crafted packets sent to port 102/tcp, which could allow an attacker to cause a denial of service in the device.

    Source: siemens_advisory, 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
    SiemensSIMATIC Drive Controller CPU 1504D TF
    • All versions < V2.9.7
    • —
    SiemensSIMATIC Drive Controller CPU 1507D TF
    • All versions < V2.9.7
    • —
    SiemensSIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants)
    • All versions < V21.9.7
    • —
    SiemensSIMATIC S7-1200 CPU family (incl. SIPLUS variants)
    • All versions < V4.6.0
    • —
    SiemensSIMATIC S7-1500 CPU 1510SP F-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1510SP-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1511-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1511C-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1511F-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1511T-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1511TF-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1512C-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1512SP F-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1512SP-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1513-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1513F-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1513R-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1515-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1515F-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1515R-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1515T-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1515TF-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1516-3 PN/DP
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1516F-3 PN/DP
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU 1516T-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1516TF-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1517-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1517F-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1517H-3 PN
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1517T-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1517TF-3 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518HF-4 PN
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518T-4 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU 1518TF-4 PN/DP
    • All versions < V3.0.1
    • —
    SiemensSIMATIC S7-1500 CPU S7-1518-4 PN/DP ODK
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 CPU S7-1518F-4 PN/DP ODK
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 ET 200pro: CPU 1513PRO F-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 ET 200pro: CPU 1513PRO-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 ET 200pro: CPU 1516PRO F-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 ET 200pro: CPU 1516PRO-2 PN
    • All versions < V2.9.7
    • —
    SiemensSIMATIC S7-1500 Software Controller V2
    • All versions < V21.9.7
    • —
    SiemensSIMATIC S7-PLCSIM Advanced
    • All versions < V5.0
    • —
    SiemensSIPLUS ET 200SP CPU 1510SP F-1 PN
    • All versions < V2.9.7
    • —
    SiemensSIPLUS ET 200SP CPU 1510SP F-1 PN RAIL
    • All versions < V2.9.7
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othersiemenssimatic_et_200_sp_open_controller_cpu_1515sp_pc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1211c_firmware—
    Othersiemenssimatic_s7-1200_cpu_1212c_firmware—
    Othersiemenssimatic_s7-1200_cpu_1212fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1214_fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1214c_firmware—
    Othersiemenssimatic_s7-1200_cpu_1214fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1215_fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1215c_firmware—
    Othersiemenssimatic_s7-1200_cpu_1215fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_1217c_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1211c_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1212c_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1212fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1214c_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1214fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1215c_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1215fc_firmware—
    Othersiemenssimatic_s7-1200_cpu_12_1217c_firmware—
    Othersiemenssimatic_s7-1500_cpu_1507s_f_firmware—
    Othersiemenssimatic_s7-1500_cpu_1507s_firmware—
    Othersiemenssimatic_s7-1500_cpu_1508s_f_firmware—
    Othersiemenssimatic_s7-1500_cpu_1508s_firmware—
    Othersiemenssimatic_s7-1500_cpu_1510sp-1_firmware—

    Weakness classes (CWE)

    • CWE-1287Improper Validation of Specified Type of Input

      Base

      The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.

      Entry at MITRE CWE-1287

    References & sources

    Embed badge

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    Badge preview for CVE-2021-44694
    <a href="https://intel.neosec.eu/en/cve/CVE-2021-44694"><img src="https://intel.neosec.eu/badge/cve/CVE-2021-44694.svg?lang=en" alt="CVE-2021-44694 – NEOSEC Intel" height="20"></a>