dbcve.org
Tew 827dru FirmwareOperating system · Trendnet

CVE-2021-20151

CRITICAL · 10.0 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 →
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
Trendnet AC2600 TEW-827DRU version 2.08B01 contains a flaw in the session management for the device. The router's management software manages web sessions based on IP address rather than verifying client cookies/session tokens/etc. This allows an attacker (whether from a different computer, different web browser on the same machine, etc.) to take over an existing session. This does require the attacker to be able to spoof or take over original IP address of the original user's session.

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 (firmware 2.08B01) implements session management based solely on client IP address rather than validating session cookies or tokens. An attacker who can spoof or takeover the victim's IP address can hijack the existing administrative session without needing valid credentials.

MitigationApply vendor-supplied firmware update when available; until then, mitigate by avoiding untrusted networks, using VPN for router administration, and implementing network segmentation to limit exposure.

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 the device model
    Locate the device label on the router physical chassis, or access the router web interface and look for the model number in the status or system information page.
    Affected if The device is not a Trendnet TEW-827DRU, then this specific CVE does not apply.
  2. Determine the firmware version via web interface
    Access the router web interface (typically at 192.168.10.1), navigate to Status or System section, and locate the firmware version field.
    Affected if The displayed firmware version is 2.08B01, then the device is running the affected version.
  3. Verify firmware version via CLI if accessible
    Connect to the router via SSH or Telnet if enabled, and run the command 'cat /proc/version' or 'nvram get firmware_version' to retrieve the firmware version.
    Affected if The reported version is 2.08B01, confirming the affected firmware.
  4. Cross-check firmware version from backup or vendor source
    If you have a backup of the firmware or downloaded the firmware from Trendnet's support page, compare the version string in the file or download metadata against 2.08B01.
    Affected if The firmware file version matches 2.08B01, indicating the device is running vulnerable firmware.

A user is affected if their Trendnet TEW-827DRU router is running firmware version 2.08B01.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor-supplied firmware update when available; until then, mitigate by avoiding untrusted networks, using VPN for router administration, and implementing network segmentation to limit exposure.

Recommended fix Moderate confidence

TEW-827DRU firmware version 2.15B01 or later (latest available version from Trendnet)

  1. 1. Navigate to the official Trendnet support page at www.trendnet.com
  2. 2. Locate the TEW-827DRU product page and access the Firmware/Downloads section
  3. 3. Download the latest available firmware version for the TEW-827DRU router
  4. 4. Access the router's web management interface using administrator credentials
  5. 5. Navigate to the Firmware Upgrade or Administration section
  6. 6. Upload and apply the downloaded firmware file
  7. 7. After the upgrade completes, verify the new firmware version in the router's status page
  8. 8. Clear existing browser sessions and reconnect to the router
Caveat Firmware upgrades may reset router configuration to defaults; backup configuration before upgrading and reapply settings after

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Tew 827dru Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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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-2021-20151 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data