CVE-2026-51673 in TOTOLINK
Summary
by MITRE • 08/31/2026
Incorrect access control in the setNtpCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to alter time synchronization settings via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
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Analysis
by VulDB Data Team • 08/31/2026
The vulnerability identified in the TOTOLINK T6 router, specifically within firmware version 4.1.5cu.748_B20211015, represents a critical failure in access control mechanisms governing system configuration functions. The core technical flaw resides in the setNtpCfg function, which is responsible for configuring Network Time Protocol settings on the device. This function fails to enforce proper authentication or authorization checks before processing incoming requests that modify these sensitive parameters. Consequently, any unauthenticated actor capable of reaching the router's web interface can interact with this endpoint without providing valid credentials. The attack vector involves sending a specifically crafted POST request to the /cgi-bin/cstecgi.cgi script, which acts as the gateway for executing administrative commands via HTTP. This lack of validation allows external or internal attackers to overwrite existing NTP server configurations with maliciously chosen time sources.
From an operational perspective, the ability to alter time synchronization settings has significant implications for network security and integrity. Accurate system time is foundational for many security protocols, including Secure Sockets Layer (SSL) certificate validation, logging mechanisms, and authentication tokens such as those used in Kerberos or OAuth flows. By manipulating NTP configurations, an attacker can cause the router to synchronize with a rogue time server under their control. This capability enables Time-of-Check-to-Time-of-Use attacks where certificates may be accepted incorrectly due to manipulated timestamps, or it allows for the disruption of audit logs by skewing system clocks, thereby hindering forensic analysis and incident response efforts. Furthermore, if the router is part of a larger network relying on synchronized time for coordinated security events, this manipulation can degrade the overall reliability and trustworthiness of the entire infrastructure.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-269, which describes Improper Privilege Assignment or Lack of Function Level Access Control. It also maps to MITRE ATT&CK technique T1547.003, specifically Boot and Logon Autostart Execution: NTP Services, although in this context it is more accurately characterized as a configuration manipulation tactic that facilitates broader system compromise rather than persistence through autostart alone. The exploitation of this flaw allows an attacker to gain indirect control over critical network behaviors without needing direct administrative access, effectively bypassing the intended security boundaries of the device's web interface.
Mitigation strategies for this vulnerability primarily involve applying vendor-provided firmware updates that patch the setNtpCfg function with proper authentication checks. Until such patches are available or deployed, administrators should restrict access to the router’s management interface by placing it behind a firewall rule that limits connectivity to trusted IP addresses only. Additionally, disabling remote administration features if they are not strictly necessary can reduce the attack surface exposed to unauthenticated actors. Network segmentation is also recommended to isolate critical infrastructure devices from general user networks, thereby limiting the potential impact of such configuration changes on broader organizational operations. Regular auditing of router configurations and monitoring for unexpected NTP server changes can help in early detection of exploitation attempts.