Description

Incorrect access control in the NTPSyncWithHost function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to change the device clock via sending a crafted POST request to /cgi-bin/cstecgi.cgi.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.1",
  "pubDate": "2026-08-31T18:17:18.197Z",
  "pubdate": "2026-08-31T18:17:18.197Z",
  "executiveSummary": "The TOTOLINK T6 router, specifically firmware version 4.1.5cu.748_B20211015, contains a critical access control vulnerability located within the NTPSyncWithHost function.\nThis flaw permits unauthenticated, remote attackers to manipulate the system's internal clock settings by submitting a maliciously crafted POST request to the /cgi-bin/cstecgi.cgi interface.\nThe lack of proper authentication or authorization checks allows unauthorized entities to alter device time configuration, which can lead to various secondary security impacts, including the invalidation of security certificates, disruption of log integrity, and potential bypass of time-based security policies or scheduled restrictions.\nThe vulnerability is categorized as an improper access control issue, indicating a failure in the application's logic to enforce security boundaries for sensitive administrative functions.\nGiven that the interface is accessible via the network, the exposure is significant, as it does not require valid credentials or local access to the device management interface to exploit.\nThe absence of verification for the source of the request enables potential attackers to perform these unauthorized modifications at will.",
  "technicalDetails": "The root cause of this vulnerability lies in the implementation of the NTPSyncWithHost function within the TOTOLINK T6 firmware version 4.1.5cu.748_B20211015. The function, which is designed to synchronize the device's system clock with an external NTP host, fails to validate the identity of the requester before processing the request.\nThe vulnerable component resides within the CGI processing layer of the device's web server, specifically accessible via the /cgi-bin/cstecgi.cgi endpoint. This endpoint serves as a gateway for various administrative operations, but it fails to enforce strict access control measures for the time synchronization process.\nThe attack flow commences when an unauthenticated attacker transmits a crafted HTTP POST request to the identified CGI binary. By manipulating the request parameters associated with the NTPSyncWithHost functionality, the attacker can force the device to update its internal clock to arbitrary timestamps.\nBecause the function lacks authentication requirements, the request is processed with the privileges of the web management service, effectively allowing the attacker to bypass authentication bypass logic.\nThe exploit does not rely on complex memory corruption techniques; rather, it exploits an architectural deficiency where administrative commands are exposed without session validation or authorization headers.\nFrom a post-exploitation perspective, the ability to arbitrarily modify the system time can have severe cascading effects on device security. Time-stamping is crucial for logging events; unauthorized modifications can facilitate anti-forensics by obscuring the timeline of unauthorized access. Furthermore, if the device utilizes time-based security, such as token expiration or scheduled firewall rules, an attacker can neutralize these protections by desynchronizing the device clock. The modification may also disrupt TLS/SSL handshake processes if the time discrepancy exceeds the acceptable drift threshold, leading to service degradation or potential Man-in-the-Middle (MitM) opportunities due to certificate validation failures."
}