How severe is CVE-2021-20156?

CVE-2021-20156 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-20156 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20156?

CVE-2021-20156 affects Trendnet Tew-827dru Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-20156?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-20156 published?

CVE-2021-20156 was published on 2021-12-30 and last updated on 2026-06-17.

CVE-2021-20156

CVE-2021-20156 is a medium-severity vulnerability in Trendnet Tew-827dru Firmware with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-347
Affected product: Trendnet Tew-827dru Firmware
Published: 2021-12-30
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-20156?: 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.
How severe is CVE-2021-20156?: CVE-2021-20156 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-20156 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20156?: CVE-2021-20156 affects Trendnet Tew-827dru Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-20156?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20156 published?: CVE-2021-20156 was published on 2021-12-30 and last updated on 2026-06-17.

References

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

Affected products (1)

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

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