CVE-2026-51760

Deferred Deferred - Pending Action

Incorrect Access Control in TOTOLINK T6 Firmware via MQTT Message

Publication date: 2026-09-01

Last updated on: 2026-09-02

Assigner: MITRE

Description

Incorrect access control in the informSyncUpgfw function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to mass-trigger firmware update activity across mesh slaves 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

2026-09-02

Generated

2026-09-21

AI Q&A

2026-09-01

EPSS Evaluated

2026-09-20

NVD

CVE-2026-51760

EUVD

EUVD-2026-69199

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 informSyncUpgfw 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 triggers mass firmware update activity across mesh slaves without proper authorization.

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 repeated firmware update triggers or unexpected mesh slave communications.

Impact Analysis

This vulnerability allows attackers to remotely initiate unauthorized firmware updates on connected devices. This could lead to device instability, potential denial of service, or even compromise of the entire mesh network. Users may experience unexpected downtime or loss of functionality in their networked devices.

Compliance Impact

This vulnerability allows unauthenticated attackers to trigger unauthorized firmware updates via crafted MQTT messages. This could lead to unauthorized access or control of devices, potentially violating data protection and privacy requirements under standards like GDPR and HIPAA.

Mitigation Strategies

Immediately isolate affected TOTOLINK T6 devices from the network. Disable unnecessary MQTT services on the device. Update to a patched firmware version if available. Monitor for unauthorized firmware update activity.

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