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Tew 827dru FirmwareOperating system · Trendnet

CVE-2021-20152

MEDIUM · 6.5 CVSS v3.1 Published 2021-12-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
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
Trendnet AC2600 TEW-827DRU version 2.08B01 lacks proper authentication to the bittorrent functionality. If enabled, anyone is able to visit and modify settings and files via the Bittorent web client by visiting: http://192.168.10.1:9091/transmission/web/

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

The Trendnet AC2600 TEW-827DRU router firmware 2.08B01 contains an authentication bypass vulnerability in its built-in BitTorrent (Transmission) client. The web interface on port 9091 is accessible without any authentication, allowing unauthenticated attackers to access, modify, and control BitTorrent settings and downloaded files.

MitigationIf the BitTorrent functionality is not required, disable it through the router administration interface. Otherwise, restrict access to the local management interface via network segmentation or firewall rules to prevent unauthorized access to port 9091 from untrusted internal hosts.

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
Tew 827dru FirmwareOperating system
Affected:= 2.08b01

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
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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 the router model
    Access the router's web interface or check the device label to confirm it is a Trendnet TEW-827DRU (AC2600) model.
    Affected if The device is not a TEW-827DRU, then it is not affected by this specific CVE.
  2. Check the firmware version
    Log into the router administration interface and navigate to the Status or System section to view the firmware version. Alternatively, check the firmware file name or the router's web page for the version number.
    Affected if The firmware version is 2.08B01, then it is within the affected version range.
  3. Verify if the BitTorrent client is enabled
    In the router web interface, look for a BitTorrent, Transmission, or Download client settings section. Check if the BitTorrent functionality has been turned on or configured.
    Affected if The BitTorrent client is disabled or not configured, then the vulnerability is not exploitable in its current state.
  4. Test access to port 9091 without credentials
    From a browser on a computer connected to the same network, navigate to http://<router-ip>:9091 or http://192.168.10.1:9091 (default gateway) without entering any username or password. Observe whether the Transmission BitTorrent web interface loads.
    Affected if The BitTorrent web interface loads without prompting for any authentication, then the vulnerability is present and the environment is affected.
  5. Confirm no authentication is required on the BitTorrent interface
    Attempt to interact with the BitTorrent client (such as adding a torrent, viewing downloads, or changing settings) without providing any login credentials.
    Affected if Actions can be performed without authentication, confirming the authentication bypass vulnerability.

The environment is affected if the device is a Trendnet TEW-827DRU running firmware 2.08B01, the BitTorrent (Transmission) client is enabled, and port 9091 is accessible without any authentication.

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

If the BitTorrent functionality is not required, disable it through the router administration interface. Otherwise, restrict access to the local management interface via network segmentation or firewall rules to prevent unauthorized access to port 9091 from untrusted internal hosts.

Fix this in Tew 827dru Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
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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-2021-20152 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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