MediumCVE-2026-4621

    NEC Platforms Aterm: Hidden Functionality (CVE-2026-4621)

    Published Last modified Sources: CVE.org

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    What is affected, what to do

    Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

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

    Affected
    • NEC Platforms Aterm W1200EX(-MS) eq All versions..All versions
    • NEC Platforms Aterm WG1200HP2 eq All versions..All versions
    • NEC Platforms Aterm WG1900HP eq All versions..All versions
    • NEC Platforms Aterm WG1200HS2 eq All versions..All versions
    • NEC Platforms Aterm WG1800HP3 eq All versions..All versions
    • NEC Platforms Aterm WG1200HP3 eq All versions..All versions
    • NEC Platforms Aterm WG1900HP2 eq All versions..All versions
    • NEC Platforms Aterm WG1200HS3 eq All versions..All versions
    • NEC Platforms Aterm WG1800HP4 eq All versions..All versions
    • NEC Platforms Aterm WG1200HP4 eq All versions..All versions
    • NEC Platforms Aterm WG1200HS4 eq All versions..All versions
    • NEC Platforms Aterm WX1500HP eq Before Ver. 1.4.2..Before Ver. 1.4.2
    • NEC Platforms Aterm WG2600HS eq Before Ver. 1.7.2..Before Ver. 1.7.2
    • NEC Platforms Aterm WF1200CR eq Before Ver. 1.6.0..Before Ver. 1.6.0
    • NEC Platforms Aterm WG1200CR eq Before Ver. 1.5.0..Before Ver. 1.5.0
    • NEC Platforms Aterm WG2600HP4 eq Before Ver. 1.4.2..Before Ver. 1.4.2
    • NEC Platforms Aterm WG2600HM4 eq Before Ver. 1.4.2..Before Ver. 1.4.2
    • NEC Platforms Aterm WG2600HS2 eq Before Ver. 1.3.2..Before Ver. 1.3.2
    • NEC Platforms Aterm WX3000HP eq Before Ver. 2.5.0..Before Ver. 2.5.0
    • NEC Platforms Aterm WX3000HP2 eq Before Ver. 1.3.2..Before Ver. 1.3.2
    • NEC Platforms Aterm WX3600HP eq Before Ver. 1.4.2..Before Ver. 1.4.2
    • NEC Platforms Aterm GX1200HP eq All versions..All versions
    • NEC Platforms Aterm GX1200HS4 eq All versions..All versions
    • NEC Platforms Aterm WG1200DM4 eq All versions..All versions
    • NEC Platforms Aterm GB1200PE eq Before Ver. 1.3.1..Before Ver. 1.3.1

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

    Metrics

    6.3

    Priority

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

    Source: Vendor (CNA), CVSS v4

    5.6

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: CVE.org

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 5.6

    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
    47.14 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
    6.3 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
    5.6
    CVSS v4

    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
    6.3
    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
    0.2 %
    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
    5.6
    Low — this CVE sits in the lower 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 27 March 2026
    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-912

    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

    Hidden Functionality vulnerability in NEC Platforms, Ltd. Aterm Series allows a attacker to enable telnet via network.

    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
    NEC Platforms, Ltd.Aterm GB1200PE
    • Before Ver. 1.3.1
    • —
    NEC Platforms, Ltd.Aterm GX1200HP
    • All versions
    • —
    NEC Platforms, Ltd.Aterm GX1200HS4
    • All versions
    • —
    NEC Platforms, Ltd.Aterm W1200EX(-MS)
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WF1200CR
    • Before Ver. 1.6.0
    • —
    NEC Platforms, Ltd.Aterm WG1200CR
    • Before Ver. 1.5.0
    • —
    NEC Platforms, Ltd.Aterm WG1200DM4
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HP2
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HP3
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HP4
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HS2
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HS3
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1200HS4
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1800HP3
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1800HP4
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1900HP
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG1900HP2
    • All versions
    • —
    NEC Platforms, Ltd.Aterm WG2600HM4
    • Before Ver. 1.4.2
    • —
    NEC Platforms, Ltd.Aterm WG2600HP4
    • Before Ver. 1.4.2
    • —
    NEC Platforms, Ltd.Aterm WG2600HS
    • Before Ver. 1.7.2
    • —
    NEC Platforms, Ltd.Aterm WG2600HS2
    • Before Ver. 1.3.2
    • —
    NEC Platforms, Ltd.Aterm WX1500HP
    • Before Ver. 1.4.2
    • —
    NEC Platforms, Ltd.Aterm WX3000HP
    • Before Ver. 2.5.0
    • —
    NEC Platforms, Ltd.Aterm WX3000HP2
    • Before Ver. 1.3.2
    • —
    NEC Platforms, Ltd.Aterm WX3600HP
    • Before Ver. 1.4.2
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othernecaterm_w1200ex-ms_firmware—
    Othernecaterm_wf1200cr_firmware—
    Othernecaterm_wg1200cr_firmware—
    Othernecaterm_wg1200hp2_firmware—
    Othernecaterm_wg1200hp3_firmware—
    Othernecaterm_wg1200hp4_firmware—
    Othernecaterm_wg1200hs2_firmware—
    Othernecaterm_wg1200hs3_firmware—
    Othernecaterm_wg1200hs4_firmware—
    Othernecaterm_wg1800hp3_firmware—
    Othernecaterm_wg1800hp4_firmware—
    Othernecaterm_wg1900hp2_firmware—
    Othernecaterm_wg1900hp_firmware—
    Othernecaterm_wg2600hm4_firmware—
    Othernecaterm_wg2600hp4_firmware—
    Othernecaterm_wg2600hs2_firmware—
    Othernecaterm_wg2600hs_firmware—
    Othernecaterm_wx1500hp_firmware—
    Othernecaterm_wx3000hp2_firmware—
    Othernecaterm_wx3000hp_firmware—
    Othernecaterm_wx3600hp_firmware—

    Weakness classes (CWE)

    • CWE-912Hidden Functionality

      Class

      The product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product's users or administrators.

      Entry at MITRE CWE-912

    References & sources

    • jpn.nec.comsecurity-info/secinfo/nv26-001_en.htmlVendor advisory

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    One NVD translation into another language is hidden.

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    Badge preview for CVE-2026-4621
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-4621"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-4621.svg?lang=en" alt="CVE-2026-4621 – NEOSEC Intel" height="20"></a>