CVE-2026-85031 in CP450
Summary
by MITRE • 09/03/2026
A vulnerability was found in TOTOLINK CP450 4.1.0. The impacted element is an unknown function of the file /cgi-bin/cstecgi.cgi. Performing a manipulation of the argument topicurl results in buffer overflow. Remote exploitation of the attack is possible.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified in TOTOLINK CP450 firmware version 4.1.0 represents a critical security flaw located within the Common Gateway Interface script /cgi-bin/cstecgi.cgi, which serves as a primary interface for administrative communication between web clients and the router's underlying system functions. This specific component is responsible for handling various configuration requests from users accessing the device via its web management portal or API endpoints. The core technical defect lies in an unknown function within this CGI script that fails to adequately validate or bound input data associated with the topicurl argument. When a remote attacker constructs a specially crafted HTTP request containing a payload exceeding the expected buffer size for this parameter, the application allocates insufficient memory space on the stack or heap, leading directly to a classic buffer overflow condition. This type of flaw is categorized under CWE-120 Buffer Copy without Checking Size of Input and often involves improper handling of input data as described in CWE-20. The lack of rigorous boundary checks allows maliciously crafted strings to overwrite adjacent memory locations, potentially corrupting the program's execution flow or overwriting critical control structures such as return addresses.
The operational impact of this vulnerability is severe due to its remote exploitable nature and the privileged context in which the CGI script typically operates. Since /cgi-bin/cstecgi.cgi often runs with elevated privileges necessary to modify router settings, successful exploitation can allow an unauthenticated attacker or a low-privileged user to execute arbitrary code on the target device. This could result in full system compromise, enabling the attacker to install persistent backdoors, exfiltrate sensitive network configuration data, or use the compromised router as a pivot point for further attacks against internal network assets. From a tactical perspective, this vulnerability aligns with ATT&CK techniques related to Initial Access via Web Services and Execution through Command and Script Interpreter, allowing adversaries to establish a foothold within enterprise networks that rely on these specific IoT devices for connectivity or segmentation. The ability to remotely trigger the overflow means that no physical access or prior authentication is strictly required if the web interface is exposed to untrusted networks, significantly expanding the attack surface beyond local network boundaries.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The most effective solution is for TOTOLINK to release a firmware update that patches this specific buffer overflow by implementing strict input validation, length checking, and safe string handling functions such as strncpy or snprintf instead of unsafe alternatives like strcpy. Until an official patch is available, network administrators should restrict access to the router's management interface using firewall rules, ensuring it is only accessible from trusted internal subnets rather than being exposed directly to the internet. Additionally, disabling unnecessary services and changing default credentials can reduce the risk profile associated with this device. Security monitoring tools should be configured to detect anomalous HTTP requests containing unusually long parameters or malformed data directed at CGI endpoints, which may indicate an attempted exploitation of this vulnerability. Regular firmware audits and adherence to secure coding standards that mandate bounds checking for all user-supplied inputs are essential preventive measures against similar classes of vulnerabilities in embedded systems.