CVE-2026-51610 Overview
CVE-2026-51610 is an incorrect access control vulnerability in the RebootSystem function of the TOTOLINK T6 router running firmware version 4.1.5cu.748_B20211015. Unauthenticated attackers on an adjacent network can force an immediate device reboot by sending a crafted HTTP POST request to /cgi-bin/cstecgi.cgi. The flaw is classified under CWE-284: Improper Access Control and results in a denial-of-service condition against the affected router.
Critical Impact
Any attacker with adjacent network access can repeatedly reboot the TOTOLINK T6 router without authentication, disrupting connectivity for all users on the network segment.
Affected Products
- TOTOLINK T6 router
- Firmware version 4.1.5cu.748_B20211015
- Web management interface exposed via /cgi-bin/cstecgi.cgi
Discovery Timeline
- 2026-08-28 - CVE-2026-51610 published to NVD
- 2026-09-01 - Last updated in NVD database
Technical Details for CVE-2026-51610
Vulnerability Analysis
The TOTOLINK T6 router exposes a Common Gateway Interface (CGI) endpoint at /cgi-bin/cstecgi.cgi that dispatches requests to internal handlers based on the request body. The RebootSystem handler triggers an immediate device restart. The endpoint fails to verify that the caller holds an authenticated administrative session before invoking this handler.
An attacker sending a crafted POST request specifying the RebootSystem function causes the router to reboot without any credential check. Because reboots interrupt all traffic passing through the device, repeated invocation results in a sustained denial of service. The vulnerability requires adjacent network access, meaning the attacker must reside on the same logical network segment such as the router's LAN or Wi-Fi.
Further details are available in the GitHub Vulnerability Report and the Vendor Coordination README.
Root Cause
The root cause is missing authorization enforcement on a privileged CGI action. The RebootSystem code path executes the reboot regardless of the authentication state of the HTTP session. There is no session token validation, cookie check, or referrer restriction guarding the reboot function.
Attack Vector
Exploitation requires network reachability to the router's web management interface, typically over the LAN or wireless network. The attacker sends a single POST request to /cgi-bin/cstecgi.cgi with a body invoking RebootSystem. No user interaction and no credentials are required. See the GitHub Vulnerability Confirmation for the confirmed exploitation flow.
No verified public exploit code is available in the referenced sources. The vulnerability mechanism can be reproduced by issuing an HTTP POST to the CGI endpoint invoking the reboot topic name, as documented in the vendor coordination reports.
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Stop Identity AttacksDetection Methods for CVE-2026-51610
Indicators of Compromise
- Unexpected router reboots recorded in device system logs
- HTTP POST requests to /cgi-bin/cstecgi.cgi from unauthenticated clients on the LAN or Wi-Fi segment
- Request bodies referencing the RebootSystem topic or function name
- Repeated short-interval loss of upstream connectivity for LAN clients
Detection Strategies
- Monitor HTTP traffic to the router management interface for POST requests targeting cstecgi.cgi that originate from non-administrator hosts.
- Correlate router uptime resets with recent inbound requests to the CGI endpoint.
- Deploy network intrusion detection signatures matching POST bodies containing the RebootSystem string directed at the T6 management IP.
Monitoring Recommendations
- Enable syslog forwarding from the router to a central collector to preserve boot and access events.
- Track the router's SNMP sysUpTime counter for unexplained resets.
- Alert on repeated authentication-free access attempts to embedded device management URLs across the network.
How to Mitigate CVE-2026-51610
Immediate Actions Required
- Restrict access to the router's web management interface to trusted administrative hosts only using LAN access control lists where supported.
- Disable wireless access to the management interface and require wired administration.
- Segment untrusted devices, including guest Wi-Fi, onto isolated VLANs that cannot reach the router's management IP.
- Monitor for and investigate any unexpected reboots of the TOTOLINK T6.
Patch Information
No vendor patch is referenced in the NVD entry at the time of publication. Consult the TOTOLINK Download Page and the TOTOLINK Official Website for firmware updates that may address the RebootSystem access control flaw. Apply any released firmware update that supersedes 4.1.5cu.748_B20211015.
Workarounds
- Block inbound requests to /cgi-bin/cstecgi.cgi from all hosts except designated administrator workstations using upstream network filtering.
- Change the default management port and disable remote management from WAN if enabled.
- Consider replacing the device if no firmware update becomes available and the router operates in a sensitive environment.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
