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Jtc 200 FirmwareOperating system · Jantek

CVE-2016-5791

CRITICAL · 9.8 CVSS v3.0 Published 2017-10-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An Improper Authentication issue was discovered in JanTek JTC-200, all versions. The improper authentication could provide an undocumented BusyBox Linux shell accessible over the TELNET service without any authentication.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A critical authentication bypass vulnerability in JanTek JTC-200 devices exposes an undocumented BusyBox Linux shell via the TELNET service, allowing unauthenticated remote attackers to gain full shell access to the device without any credentials.

MitigationRestrict network access to the TELNET port via firewall rules or network segmentation, and contact JanTek for a firmware update to remove or properly secure the undocumented shell.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Jtc 200 FirmwareOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if the device is a JanTek JTC-200
    Determine if the target device is a JanTek JTC-200 unit by checking device labeling, firmware version via SNMP, HTTP admin interface, or network documentation
    Affected if The device is confirmed to be a JanTek JTC-200
  2. Check if TELNET service is exposed
    Scan for open TELNET port (TCP 23) on the target device or attempt a connection to port 23
    Affected if TELNET port 23 is accessible from an external or untrusted network
  3. Verify unauthenticated shell access
    Connect to the TELNET port and observe whether a BusyBox shell prompt appears immediately without requiring any login credentials
    Affected if A shell prompt is returned without any authentication challenge

If the device is a JanTek JTC-200 with TELNET port 23 exposed and accessible without credentials, the environment is affected by this vulnerability

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Restrict network access to the TELNET port via firewall rules or network segmentation, and contact JanTek for a firmware update to remove or properly secure the undocumented shell.

Fix this in Jtc 200 Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,980
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-5791 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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