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CVE-2021-20156

22
FAUCET Score

CVE-2021-20156 describes an improper access control vulnerability in Trendnet AC2600 TEW-827DRU version 2.08B01, allowing for the installation of malicious firmware due to a lack of signature validation. An authenticated attacker can manually install untrusted firmware or, by masquerading as the update server, push malicious updates even through the automated update mechanism. This vulnerability carries a CVSS score of 6.5 (Medium), indicating a network-based attack with low complexity, requiring low privileges, and resulting in high integrity impact (malicious firmware installation). Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
2.08b01CPE matchmatch criteria
cpe:2.3:o:trendnet:tew-827dru_firmware:2.08b01:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.41%
Probability of exploitation in next 30 days
EPSS Percentile
33.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0041 is in the 43rd percentile among its peer group of 21,977 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (3)

giteavendor investigatingvia llm_extracted
opensshvendor investigatingvia llm_extracted
railsvendor investigatingvia llm_extracted

Vendor Advisories (3)

opensshllm-openssh-45a77a1aa1e5a984CRITICAL

Trendnet AC2600 TEW-827DRU Multiple Vulnerabilities

Dec 30, 2021
giteallm-gitea-3b028f48a893fc43CRITICAL

Trendnet AC2600 TEW-827DRU Multiple Vulnerabilities

Dec 30, 2021
railsllm-rails-32c592b9c1e5a4e5CRITICAL

Trendnet AC2600 TEW-827DRU Multiple Vulnerabilities

Dec 30, 2021

References

tenable.com / security/research/tra-2021-54
Third Party Advisory