CVE-2026-51620 in TOTOLINK
Summary
by MITRE • 08/28/2026
Incorrect access control in the getNetInfoCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain network topology and interface configuration information via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
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Analysis
by VulDB Data Team • 08/28/2026
The vulnerability identified in TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015 represents a critical failure in access control mechanisms within the device's web management interface. Specifically, the flaw resides in the getNetInfoCfg function, which is designed to retrieve network topology and interface configuration details for administrative purposes. Under normal operational conditions, such sensitive information should be restricted to authenticated users with appropriate privileges to prevent unauthorized disclosure of internal network structures. However, due to insufficient validation checks within this specific CGI endpoint, unauthenticated attackers can bypass authentication requirements entirely. By sending a crafted POST request to the /cgi-bin/cstecgi.cgi path, an attacker can successfully invoke this function and receive detailed responses containing sensitive network data without providing any credentials or session tokens.
This type of vulnerability is classified under CWE-284, which describes Improper Access Control, indicating that the software does not properly restrict access to a resource for unauthorized actors. The exploitation vector aligns with ATT&CK technique T1078, Valid Accounts, although in this specific instance, it allows information disclosure even without valid accounts due to the lack of authentication enforcement on the endpoint itself. This falls under the broader category of Information Exposure (CWE-200), where sensitive system configuration data is made available to adversaries who should not have access to it. The ability to retrieve network topology and interface configurations provides attackers with a comprehensive map of the internal network, including IP addresses, subnet masks, gateway information, and potentially connected device identifiers.
The operational impact of this vulnerability extends beyond simple information disclosure. With knowledge of the network topology, an attacker can perform more targeted attacks against other devices on the local area network. For instance, knowing the specific interface configurations allows for precise ARP spoofing or DNS hijacking attempts that are less likely to be detected by standard intrusion detection systems because they mimic legitimate traffic patterns associated with known internal services. Furthermore, this information facilitates lateral movement within the network environment, enabling attackers to identify high-value targets such as servers, IoT devices, or other routers based on their configuration profiles and connectivity status. In environments where these routers serve as gateways for critical infrastructure or sensitive corporate data, this exposure significantly increases the attack surface and reduces the effectiveness of perimeter defenses.
Mitigation strategies must address both immediate remediation and long-term security posture improvements. The primary solution is to apply the vendor-provided firmware update that patches the access control logic in the getNetInfoCfg function, ensuring that authentication checks are enforced before any sensitive data is returned. Until such updates are available or deployed, network administrators should implement strict firewall rules at the perimeter level to restrict direct HTTP/HTTPS access to the router's management interface from untrusted networks. Additionally, placing the administrative interface on a dedicated VLAN with restricted IP whitelisting can significantly reduce exposure. It is also recommended to disable remote management features if they are not strictly necessary for operational requirements, thereby eliminating the external attack vector entirely. Regular security audits and penetration testing should be conducted to identify similar misconfigurations in other CGI endpoints or API functions that may suffer from analogous access control failures.