CVE-2026-51747

Deferred Deferred - Pending Action

Incorrect Access Control in TOTOLINK T6 Firmware via MQTT Message

Publication date: 2026-09-01

Last updated on: 2026-09-03

Assigner: MITRE

Description

Incorrect access control in the keepAlive function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to emit indirect mesh heartbeat information toward the master via sending a crafted MQTT message to the cs_broker component.

CVSS Scores

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Meta Information

Published

2026-09-01

Last Modified

2026-09-03

Generated

2026-09-21

AI Q&A

2026-09-01

EPSS Evaluated

2026-09-20

NVD

CVE-2026-51747

EUVD

EUVD-2026-69207

Affected Vendors & Products

Vendor	Product	Version / Range
totolink	t6	4.1.5cu.748_b20211015

Helpful Resources

Exploitability

CWE

KEV

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

Attack-Flow Graph

Executive Summary

This vulnerability involves incorrect access control in the keepAlive function of TOTOLINK T6 firmware version 4.1.5cu.748_B20211015. An unauthenticated attacker can exploit it by sending a specially crafted MQTT message to the cs_broker component. This allows the attacker to send indirect mesh heartbeat information to the master device.

Detection Guidance

Detecting this vulnerability requires monitoring MQTT traffic for unauthorized messages sent to the cs_broker component. Check for unexpected heartbeat messages from unauthenticated sources. Use network monitoring tools like Wireshark to capture and analyze MQTT protocol traffic on port 1883 or 8883.

Impact Analysis

An attacker could use this flaw to send unauthorized heartbeat signals, potentially disrupting the mesh network or gaining control over the master device. This may lead to network instability or unauthorized access to connected systems.

Compliance Impact

This vulnerability allows unauthenticated attackers to send crafted MQTT messages, potentially exposing mesh heartbeat data. This could lead to unauthorized access or data leakage, which may violate GDPR's data protection requirements or HIPAA's safeguards for protected health information if exploited.

Mitigation Strategies

Immediately update TOTOLINK T6 firmware to the latest patched version. Disable unnecessary MQTT services on the device if possible. Monitor network traffic for unusual MQTT messages directed at the cs_broker component.

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