CVE-2021-20156

mediumpriority · track · 26EPSS 0.004 · 36 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.42% (36th) EPSS

CVSS 4 · medium

Is it mine?

2 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.04mediumAV:N/AC:L/Au:S/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 8 · impact 2.9

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 3.6

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-347USprimary

affected products (2)

Products and version ranges known to be affected.

n/a Trendnet AC2600 TEW-827DRU≤ 2.08B01enisa_euvdEU
trendnet tew-827dru firmware= 2.08b01nvdUScpe:2.3:o:trendnet:tew-827dru_firmware:*:*:*:*:*:*:*:*

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2021-12-30modified 2026-06-17

related (1,048)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2026-67276US	high8.1OT critical	8.94% (95th)	Exploit	2026-09-05
RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking the key type and modulus but omitting the expo…
CVE-2026-5430US	—OT critical	22.4% (98th)	KEV	2026-08-06
The JWT authentication mechanism accepts tokens signed with algorithms other than those explicitly configured or supported. This allows an attacker to craft a JWT with an unsupport…
CVE-2026-48558US	—OT critical	77.7% (100th)	KEV	2026-06-12
SimpleHelp versions 5.5.15 and prior and 6.0 pre-release versions contain an authentication bypass vulnerability in the OIDC authentication flow. When OIDC authentication is config…
CVE-2025-59719US	—OT critical	29.2% (98th)	—	2025-12-09
An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticate…
CVE-2025-59718US	—OT critical	68.3% (99th)	KEV	2025-12-09
A improper verification of cryptographic signature vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11, FortiOS 7.0.0 t…

+1043 more

references (4)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan