Cyber Posture

CVE-2026-1638

Medium

Published: 30 January 2026

Published
30 January 2026
Modified
09 March 2026
KEV Added
—
Patch
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CVSS Score 6.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
EPSS Score 0.0014 33.1th percentile
Risk Priority 13 60% EPSS · 20% KEV · 20% CVSS

Description

A security flaw has been discovered in Tenda AC21 1.1.1.1/1.dmzip/16.03.08.16. The impacted element is the function mDMZSetCfg of the file /goform/mDMZSetCfg. The manipulation of the argument dmzIp results in command injection. The attack can be executed remotely. The exploit has…

more

been released to the public and may be used for attacks.

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match
prevent

Directly mitigates the command injection vulnerability by requiring validation of the dmzIp argument in the mDMZSetCfg function to block malicious payloads.

SI-2 Flaw Remediation good match
prevent

Requires timely identification, reporting, and correction of the specific command injection flaw in Tenda AC21 firmware.

SI-9 Information Input Restrictions partial match
prevent

Enforces restrictions on dmzIp inputs such as length and format to limit opportunities for command injection payloads.

Security SummaryAI

CVE-2026-1638 is a command injection vulnerability (CWE-74, CWE-77) affecting Tenda AC21 routers on firmware version 1.1.1.1/1.dmzip/16.03.08.16. The flaw resides in the mDMZSetCfg function within the /goform/mDMZSetCfg file, where manipulation of the dmzIp argument enables arbitrary command execution.

The vulnerability is remotely exploitable over the network (AV:N) with low attack complexity (AC:L), requiring low privileges (PR:L) and no user interaction (UI:N), with unchanged scope (S:U). Successful exploitation yields low impacts on confidentiality, integrity, and availability (C:L/I:L/A:L), for an overall CVSS v3.1 base score of 6.3. An exploit has been publicly released, enabling attacks by remote authenticated users with minimal privileges.

Advisories detail the issue on VulDB (ctiid.343417, id.343417, submit.740871) and a GitHub repository issue (LX-LX88/cve/issues/26), with the vendor site at tenda.com.cn listed as a reference. No specific patch or mitigation steps are outlined in the disclosure summary.

The public exploit release heightens the risk of real-world exploitation against unpatched Tenda AC21 devices.

Details

CWE(s)
CWE-74CWE-77

Affected Products

tenda
ac21 firmware
16.03.08.16

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.008 Network Device CLI Execution
Adversaries may abuse scripting or built-in command line interpreters (CLI) on network devices to execute malicious command and payloads.
attack.mitre.org →
Why these techniques?

Command injection in public-facing router web interface enables exploitation of public-facing applications (T1190) and arbitrary command execution via network device CLI (T1059.008).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

References