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Tew 827Dru Firmware CVE-2021-20149

CRITICAL
Incorrect Authorization (CWE-863)
2021-12-30 vulnreport@tenable.com
Authentication Bypass Tew 827Dru Firmware Trendnet
9.8
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-863
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization logic validation
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived

A remote attacker could bypass authorization checks to access restricted resources by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 1.4% exploitation probability (EPSS)

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AnalysisAI

Trendnet AC2600 TEW-827DRU version 2.08B01 does not have sufficient access controls for the WAN interface. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Review and test authorization logic, implement consistent access control checks, use centralized authorization framework.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified as Incorrect Authorization (CWE-863), which allows attackers to bypass authorization checks to access restricted resources. Trendnet AC2600 TEW-827DRU version 2.08B01 does not have sufficient access controls for the WAN interface. The default iptables ruleset for governing access to services on the device only apply to IPv4. All services running on the devices are accessible via the WAN interface via IPv6 by default. Affected products include: Trendnet Tew-827Dru Firmware. Version information: version 2.08.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Trendnet AC2600 TEW-827DRU version 2.08B01 does not have sufficient access controls for the WAN interface. The default iptables ruleset for governing access to services on the device only apply to IPv4. All services running on the devices are accessible via the WAN interface via IPv6 by default.

Threat Intelligence Overview

EPSS Score
1.4%
Top 30% exploitable
Data Quality
2 sources
Confidence: Low
NVD CVE.org EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 1.4%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

50
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)NVD

cpe:2.3:o:trendnet:tew-827dru_firmware:2.08b01:*:*:*:*:*:*:*

More in Tew 827Dru Firmware

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CVE-2024-28354 CRITICAL POC
10.0 Mar 15

There is a command injection vulnerability in the TRENDnet TEW-827DRU router with firmware version 2.10B01. Rated critic
CVE-2021-20158 CRITICAL POC
9.8 Dec 30

Trendnet AC2600 TEW-827DRU version 2.08B01 contains an authentication bypass vulnerability. Rated critical severity (CVS
CVE-2021-20155 CRITICAL POC
9.8 Dec 30

Trendnet AC2600 TEW-827DRU version 2.08B01 makes use of hardcoded credentials. Rated critical severity (CVSS 9.8), this

CVE-2019-13279 CRITICAL POC
9.8 Jul 10

TRENDnet TEW-827DRU with firmware up to and including 2.04B03 contains multiple stack-based buffer overflows when proces
CVE-2019-13278 CRITICAL POC
9.8 Jul 10

TRENDnet TEW-827DRU with firmware up to and including 2.04B03 contains multiple command injections when processing user

CVE-2019-13276 CRITICAL POC
9.8 Jul 10

TRENDnet TEW-827DRU with firmware up to and including 2.04B03 contains a stack-based buffer overflow in the ssi binary.

CVE-2024-28353 HIGH POC
8.8 Mar 15

There is a command injection vulnerability in the TRENDnet TEW-827DRU router with firmware version 2.10B01. Rated high s
CVE-2021-20165 HIGH POC
8.8 Dec 30

Trendnet AC2600 TEW-827DRU version 2.08B01 does not properly implement csrf protections. Rated high severity (CVSS 8.8),
CVE-2021-20160 HIGH POC
8.8 Dec 30

Trendnet AC2600 TEW-827DRU version 2.08B01 contains a command injection vulnerability in the smb functionality of the de
CVE-2021-20159 HIGH POC
8.8 Dec 30

Trendnet AC2600 TEW-827DRU version 2.08B01 is vulnerable to command injection. Rated high severity (CVSS 8.8), this vuln
CVE-2020-14076 HIGH POC
8.8 Jun 15

TRENDnet TEW-827DRU devices through 2.06B04 contain a stack-based buffer overflow in the ssi binary. Rated high severity
CVE-2019-13280 HIGH POC
8.8 Jul 09

TRENDnet TEW-827DRU with firmware up to and including 2.04B03 contains a stack-based buffer overflow while returning an

Same weakness CWE-863 – Incorrect Authorization

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CVE-2023-21715 HIGH
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CVE-2025-21480 HIGH
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CVE-2025-21479 HIGH
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CVE-2025-32462 HIGH POC
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Same technique Authentication Bypass

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CVE-2015-3306 CRITICAL POC
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CVE-2023-22515 CRITICAL POC
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CVE-2012-4681 CRITICAL POC
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CVE-2013-2465 CRITICAL POC
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CVE-2011-3544 CRITICAL POC
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CVE-2022-40684 CRITICAL POC
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CVE-2025-61882 CRITICAL POC
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CVE-2024-0012 CRITICAL POC
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References

Advisories & patches
REF https://www.tenable.com/security/research/tra-2021-54

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