CVE-2026-5104 Overview
A command injection vulnerability has been identified in Totolink A3300R firmware version 17.0.0cu.557_b20221024. The vulnerability exists in the setStaticRoute function within the /cgi-bin/cstecgi.cgi file. Improper handling of the ip argument allows attackers to inject and execute arbitrary commands on the affected device. This vulnerability can be exploited remotely over the network by authenticated attackers.
Critical Impact
Remote attackers with low privileges can exploit this command injection vulnerability to execute arbitrary commands on the Totolink A3300R router, potentially gaining unauthorized access to the device and the network it protects.
Affected Products
- Totolink A3300R Firmware version 17.0.0cu.557_b20221024
- Totolink A3300R Hardware
Discovery Timeline
- 2026-03-30 - CVE-2026-5104 published to NVD
- 2026-03-30 - Last updated in NVD database
Technical Details for CVE-2026-5104
Vulnerability Analysis
This command injection vulnerability (CWE-77) affects the setStaticRoute function in the Totolink A3300R router's CGI interface. The vulnerability stems from insufficient input validation of the ip parameter, which is passed directly to system command execution without proper sanitization. An attacker can craft malicious input containing shell metacharacters or command separators to inject arbitrary commands that execute with the privileges of the web server process running on the router.
The exploit has been publicly disclosed, increasing the risk of widespread exploitation. Router compromise could lead to network traffic interception, configuration tampering, pivot attacks against internal network resources, or recruitment into botnet infrastructure.
Root Cause
The root cause is an injection flaw (CWE-74) where user-supplied input in the ip argument is not properly validated or sanitized before being used in command execution context. The setStaticRoute function fails to implement adequate input filtering, allowing shell command syntax to pass through and be interpreted by the underlying operating system.
Attack Vector
The attack is network-based and requires low-privilege authentication to the router's web interface. Once authenticated, an attacker can send specially crafted HTTP requests to the /cgi-bin/cstecgi.cgi endpoint, targeting the setStaticRoute function with a malicious ip parameter value containing injected commands.
The vulnerability can be exploited by manipulating the ip parameter to include command injection payloads. Attackers typically use shell metacharacters such as semicolons, pipes, or command substitution syntax to append malicious commands to the legitimate static route configuration request. For detailed exploitation information, refer to the GitHub PoC Repository.
Detection Methods for CVE-2026-5104
Indicators of Compromise
- Unusual HTTP requests to /cgi-bin/cstecgi.cgi containing shell metacharacters in the ip parameter
- Unexpected processes spawned by the router's web server process
- Outbound network connections from the router to unknown external hosts
- Modifications to router configuration or system files
Detection Strategies
- Monitor HTTP traffic to the router's management interface for requests containing command injection patterns in URL parameters or POST data
- Implement network-based intrusion detection rules to alert on suspicious CGI requests targeting setStaticRoute with anomalous input
- Review router access logs for authentication events followed by requests to /cgi-bin/cstecgi.cgi
Monitoring Recommendations
- Enable and centralize logging from the router's management interface
- Configure alerts for multiple failed authentication attempts followed by successful logins
- Monitor for DNS queries or network connections originating from the router to unexpected destinations
How to Mitigate CVE-2026-5104
Immediate Actions Required
- Restrict access to the router's web management interface to trusted IP addresses only
- Disable remote management if not required for operations
- Implement network segmentation to limit exposure of the router's management interface
- Monitor for firmware updates from Totolink addressing this vulnerability
Patch Information
At the time of publication, no vendor security patch has been released for this vulnerability. Organizations should check the Totolink Official Website regularly for firmware updates addressing CVE-2026-5104. Additional vulnerability details are available at VulDB #354129.
Workarounds
- Configure firewall rules to block external access to the router's management interface on ports 80/443
- Use a VPN for remote administration instead of exposing the web interface directly
- Implement access control lists (ACLs) limiting management access to specific administrator workstations
- Consider replacing vulnerable devices with alternative hardware if no patch becomes available
# Example iptables rules to restrict management interface access
# Allow management access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
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.
