CVE-2021-20156

Name: CVE-2021-20156
Creator: NVD / NIST
Published: 2021-12-30T22:15:08.893+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.41%

Last modified Jun 17, 2026

CVE-2021-20156 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Trendnet AC2600 TEW-827DRU version 2.08B01 contains an improper access control configuration that could allow for a malicious firmware update. It is possible to manually install firmware that may be malicious in nature as there does not appear to be any signature validation done to determine if it is from a known and trusted source. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

Description

Trendnet AC2600 TEW-827DRU version 2.08B01 contains an improper access control configuration that could allow for a malicious firmware update. It is possible to manually install firmware that may be malicious in nature as there does not appear to be any signature validation done to determine if it is from a known and trusted source. This includes firmware updates that are done via the automated "check for updates" in the admin interface. If an attacker is able to masquerade as the update server, the device will not verify that the firmware updates downloaded are legitimate.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.41%

32.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-347

Affected Software

Vendor	Product	Versions
Trendnet	Tew-827dru Firmware	2.08b01

References

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

Timeline

Published: Dec 30, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20156?

How severe is CVE-2021-20156?

CVE-2021-20156 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20156?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20156?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST