CVE-2021-20161
Description
Trendnet AC2600 TEW-827DRU version 2.08B01 does not have sufficient protections for the UART functionality. A malicious actor with physical access to the device is able to connect to the UART port via a serial connection. No username or password is required and the user is given a root shell with full control of the device.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Trendnet AC2600 TEW-827DRU firmware 2.08B01 exposes an unprotected UART console, allowing a physical attacker to gain root shell access with no authentication.
Vulnerability
Trendnet AC2600 TEW-827DRU firmware version 2.08B01 lacks sufficient protections for the UART functionality. A malicious actor with physical access to the device can connect to the UART port via a serial connection. No authentication is required, and the user is presented with a root shell, granting full control of the device [1].
Exploitation
The attacker must have physical access to the device to physically connect a serial cable to the UART port. No credentials or prior network access are needed. Once connected, the attacker can directly interact with the console and obtain a root shell without any further steps [1].
Impact
A successful exploitation grants the attacker a root shell with full control over the device. This includes the ability to execute arbitrary commands, modify firmware, exfiltrate sensitive data, and pivot to other devices on the network. The compromise is complete and at the highest privilege level [1].
Mitigation
As of the publication date, no firmware update has been released to address this issue. Users should consider the device physically secured in a locked environment to prevent unauthorized physical access. There are no workarounds that can be applied via software configuration. This vulnerability is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog [1].
AI Insight generated on May 27, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2- Trendnet/AC2600 TEW-827DRUdescription
- Range: = 2.08B01
Patches
0No patches discovered yet.
Vulnerability mechanics
Root cause
"The UART console on the device does not require any authentication, allowing anyone with physical serial access to obtain a root shell."
Attack vector
An attacker must have physical access to the device to connect to the UART port via a serial connection [ref_id=1]. No username or password is required at the UART console, and the attacker is immediately granted a root shell with full control of the device [ref_id=1]. This is a physical-access attack vector (AV:P) that bypasses all software authentication controls [ref_id=1].
Affected code
The advisory does not specify a particular function or file path for the UART vulnerability. The UART functionality on the Trendnet AC2600 TEW-827DRU (version 2.08B01) lacks authentication protections at the hardware serial port level [ref_id=1].
What the fix does
The advisory does not include a patch or remediation guidance for this vulnerability [ref_id=1]. To close the vulnerability, the vendor would need to implement authentication on the UART console (e.g., requiring a username and password before granting shell access) or disable the UART root shell in production firmware. No fix has been published in the disclosed advisory [ref_id=1].
Preconditions
- networkAttacker must have physical access to the device to connect to the UART port
- inputAttacker needs a serial cable and terminal to connect to the UART header on the device's circuit board
Generated on May 25, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
1- www.tenable.com/security/research/tra-2021-54mitrex_refsource_MISC
News mentions
0No linked articles in our index yet.