CVE-2026-51761
Deferred Deferred - Pending Action

Incorrect Access Control in TOTOLINK T6 Firmware

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: MITRE

Description
Incorrect access control in the updateLanIp function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to refresh the LAN address state via sending a crafted MQTT message to the cs_broker component.

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Meta Information

Published
2026-09-01
Last Modified
2026-09-01
Generated
2026-09-22
AI Q&A
2026-09-01
EPSS Evaluated
2026-09-20
NVD
CVE-2026-51761
EUVD
EUVD-2026-69198

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
totolink t6 4.1.5cu.748_b20211015

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-284 The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

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Executive Summary

This vulnerability is an incorrect access control issue in the TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015. It allows unauthenticated attackers to manipulate the LAN IP address state by sending a specially crafted MQTT message to the cs_broker component.

Detection Guidance

To detect this vulnerability, monitor network traffic for unauthorized MQTT messages sent to the cs_broker component on TOTOLINK T6 devices. Check for unexpected LAN IP address state changes without authentication. Use packet capture tools like tcpdump or Wireshark to inspect MQTT traffic on port 1883.

Impact Analysis

An attacker could exploit this to disrupt network operations by changing the LAN IP configuration, potentially causing network outages or unauthorized access to connected devices.

Compliance Impact

This vulnerability allows unauthenticated attackers to manipulate network configurations, which could lead to unauthorized access to sensitive data or systems. Such access could violate compliance requirements under GDPR (data protection) and HIPAA (healthcare data privacy) by enabling data breaches or unauthorized network access.

Mitigation Strategies

Immediately update the TOTOLINK T6 firmware to the latest version to address the incorrect access control in the updateLanIp function. Disable unnecessary MQTT services or restrict access to the cs_broker component to prevent unauthenticated message injection.

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