EUVD-2026-69199
GHSA-4j88-2p5m-hm62
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated remote MQTT trigger with no user interaction (AV:N/AC:L/PR:N/UI:N), but the function only writes/triggers firmware sync, so no confidentiality read (C:N) while integrity and availability are high.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
Unauthenticated firmware-update abuse in the TOTOLINK T6 mesh router (firmware 4.1.5cu.748_B20211015) lets a remote attacker mass-trigger firmware update activity across all mesh slave nodes by publishing a crafted MQTT message to the internal cs_broker component. The informSyncUpgfw handler performs no access control (CWE-284), so any actor able to reach the broker can initiate the sync-upgrade workflow fleet-wide. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to be able to publish a crafted MQTT message to the TOTOLINK T6's internal cs_broker component and invoke the informSyncUpgfw handler; no authentication is required (PR:N) and no user interaction is needed. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H = 9.8) treats this as a full-impact remote unauthenticated compromise, but that appears overstated: informSyncUpgfw is a write/trigger action that initiates firmware-sync activity, not a data-read primitive, so a Confidentiality:High rating is not supported by the description - the realistic impact is integrity/availability (mass, unwanted firmware update activity that can disrupt or brick mesh slaves). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | No vendor-released patched firmware version is identified in the provided data at time of analysis; monitor the TOTOLINK download page (https://www.totolink.net/home/menu/detail/menu_listtpl/download/id/190/ids/36.html) and the vendor-coordination trackers for an updated build superseding 4.1.5cu.748_B20211015. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory all TOTOLINK T6 devices and verify firmware version 4.1.5cu.748_B20211015 exposure, then implement network segmentation to restrict MQTT broker access from untrusted networks and enable logging of broker traffic. …
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Same weakness CWE-284 – Improper Access Control
View allSame technique Authentication Bypass
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External POC / Exploit Code
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