CriticalCVE-2026-129352

    TRENDnet TEW-657BRM upgrade_flash.cgi stack-based overflow (CVE-2026-129352)

    Published Last modified Sources: CVE.org

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    What is affected, what to do

    A vulnerability was detected in TRENDnet TEW-657BRM 1.00.1. This issue affects some unknown processing of the file /usr/sbin/upgrade_flash.cgi.

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

    Affected
    • TRENDnet TEW-657BRM eq 1.00.1..1.00.1

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

    Metrics

    9.4

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    9.1

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org

    —

    EPSS score

    No value is available for this vulnerability.

    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
    77.00 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
    9.4 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
    9.1
    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
    9.4
    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, CWE-119

    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 was detected in TRENDnet TEW-657BRM 1.00.1. This issue affects some unknown processing of the file /usr/sbin/upgrade_flash.cgi. Performing a manipulation of the argument boundary results in stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit is now public and may be used. The vendor explains: ""I am not able to confirm if such vulnerability exists as the product has been EOL for more than 15 years. We will send out an announcement letting customers know."

    Source: cvelistv5, CVE.org (MITRE), NVD (NIST)

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othertrendnettew-657brm_firmware—
    Operating systemTRENDnetTEW-657BRM—

    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

    • CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer

      Class

      The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

      Entry at MITRE CWE-119

    References & sources

    • github.comruanyi101/router-firmware-security-advisories/blob/main/router-…Exploit, Patch
    • vuldb.comCVE-2026-129352 | CVE Analysis and ReportThird-party advisory
    • vuldb.comSubmit #1043522 | TRENDnet TEW-657BRM 1.00.1 Stack-based Buffer OverflowThird-party advisory
    • vuldb.comVDB-437398 | TRENDnet TEW-657BRM upgrade_flash.cgi stack-based overflowVulnerability database, Technical description
    • vuldb.comVDB-437398 | CTI Indicators (IOB, IOC, IOA)signature, Permissions required

    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).

    1. ReceivedVulDB

      CVSS V4.0: AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P

      CVSS V3.1: AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

      CVSS V2: (AV:N/AC:L/Au:M/C:C/I:C/A:C)

      Weakness type: CWE-119, CWE-121

      Description added or changed

      Show 12 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      A vulnerability was detected in TRENDnet TEW-657BRM 1.00.1. This issue affects some unknown processing of the file /usr/sbin/upgrade_flash.cgi. Performing a manipulation of the argument boundary results in stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit is now public and may be used. The vendor explains: ""I am not able to confirm if such vulnerability exists as the product has been EOL for more than 15 years. We will send out an announcement letting customers know."
      CVSSadded
      —
      AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      CVSSadded
      —
      AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
      CVSSadded
      —
      (AV:N/AC:L/Au:M/C:C/I:C/A:C)
      Weakness type (CWE)added
      —
      CWE-119
      Weakness type (CWE)added
      —
      CWE-121
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/129xxx/CVE-2026-129352.json">CVE-2026-129352</a>
      Referenceadded
      —
      https://github.com/ruanyi101/router-firmware-security-advisories/blob/main/router-firmware-GitHub-advisories/advisories/TRENDnet-TEW-657BRM-upgrade_flash.md
      Referenceadded
      —
      https://vuldb.com/cve/CVE-2026-129352
      Referenceadded
      —
      https://vuldb.com/submit/1043522
      Referenceadded
      —
      https://vuldb.com/vuln/437398
      Referenceadded
      —
      https://vuldb.com/vuln/437398/cti

      Source identifier: cna@vuldb.com

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