CVE-2026-38064 Overview
CVE-2026-38064 is a command injection vulnerability affecting the Tenda 5G03 router running firmware version V05.03.02.04 (Version 1.0). The flaw resides in the action_dial_call function, where the dialNumber parameter is passed to a system command without proper sanitization. An unauthenticated remote attacker can inject arbitrary operating system commands that execute with the privileges of the web service. Because the device is a network-edge router, successful exploitation grants attackers control over a trusted network gateway. The vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command.
Critical Impact
Unauthenticated remote attackers can execute arbitrary OS commands on the router, leading to full device compromise, traffic interception, and pivoting into the internal network.
Affected Products
- Tenda 5G03 router
- Firmware version V05.03.02.04
- Version 1.0
Discovery Timeline
- 2026-06-15 - CVE-2026-38064 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-38064
Vulnerability Analysis
The vulnerability resides in the action_dial_call function exposed by the Tenda 5G03 router's web management interface. This function processes a dialNumber parameter supplied by the client and forwards the value into an underlying operating system command, likely through a system() or popen() style call.
Because the firmware does not validate or sanitize shell metacharacters, an attacker can append additional commands using separators such as ;, |, &&, or backticks. The injected payload executes with the privileges of the embedded web server process, which on Tenda devices typically runs as root. Attack complexity is low and no authentication is required.
The EPSS probability is 1.046% with a percentile of 59.7, indicating moderate exploitation likelihood relative to other vulnerabilities.
Root Cause
The root cause is improper neutralization of special elements in an OS command [CWE-78]. The action_dial_call handler concatenates attacker-controlled input from the dialNumber HTTP parameter directly into a shell command string. No allowlist validation, input length restriction, or argument escaping is applied before execution.
Attack Vector
The attack vector is network-based. An attacker sends a crafted HTTP request to the router's web management endpoint that invokes action_dial_call with a malicious dialNumber value containing shell metacharacters. The crafted payload terminates the intended command and appends arbitrary commands such as reverse shells, persistence implants, or configuration modifications. See the GitHub IoT Vulnerability PoC for technical reproduction details.
Detection Methods for CVE-2026-38064
Indicators of Compromise
- HTTP POST or GET requests to the router's management interface containing the action_dial_call action with shell metacharacters (;, |, &, `, $()) in the dialNumber parameter.
- Unexpected outbound connections originating from the router to attacker-controlled infrastructure.
- Unauthorized modification of router DNS, routing, or firewall configuration.
Detection Strategies
- Inspect web traffic destined for Tenda 5G03 management endpoints for requests containing the dialNumber parameter combined with shell metacharacters.
- Deploy network IDS signatures that flag command injection patterns against IoT and SOHO router management URIs.
- Correlate router-originated outbound traffic with HTTP requests to the device administrative interface.
Monitoring Recommendations
- Log and review all administrative access to the Tenda 5G03 web interface, restricting it to trusted management VLANs.
- Monitor DNS query patterns from the router for anomalies indicating configuration tampering.
- Track firmware version and configuration baselines to detect unauthorized changes.
How to Mitigate CVE-2026-38064
Immediate Actions Required
- Disable remote (WAN-side) administration on affected Tenda 5G03 devices immediately.
- Restrict access to the LAN-side management interface to a dedicated administrative network segment.
- Replace devices that cannot be patched or isolated, particularly when deployed in business or sensitive environments.
Patch Information
No vendor patch is referenced in the available advisory data. Affected operators should monitor Tenda's official support channels for updated firmware releases addressing the action_dial_call handler.
Workarounds
- Place the router behind an upstream firewall that blocks access to the management web interface from untrusted networks.
- Disable any unused services or features that expose the action_dial_call endpoint.
- Apply network segmentation so that compromise of the router does not provide a direct path to sensitive internal assets.
# Example: restrict router management interface to a trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
