What is the CVSS score of CVE-2026-51765?

CVE-2026-51765 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

Which versions of TOTOLINK T6 are affected by CVE-2026-51765?

TOTOLINK T6 routers are vulnerable to remote, unauthenticated attacks that could poison the mesh network's neighbor table, potentially causing misconfiguration or connectivity issues.

How to fix or mitigate CVE-2026-51765?

Within 24 hours, identify which TOTOLINK T6 routers in your environment use mesh networking and assess business criticality. Within 7 days, restrict MQTT broker access to authorized mesh devices only using firewall rules, and segment the mesh network from non-mesh infrastructure if feasible. Within 30 days, contact TOTOLINK support to inquire about patch availability and expected release timeline; if no patch is available within 60 days, plan device replacement for non-critical deployments and implement monitoring for unexpected mesh topology changes.

TOTOLINK T6 CVE-2026-51765

EUVD-2026-69194 CRITICAL

Improper Access Control (CWE-284)

2026-09-01 mitre

GHSA-27pw-48fp-7xr2

Authentication Bypass TOTOLINK

9.8

CVSS 3.1 · Vendor: mitre

Severity by source

Vendor (mitre) PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vuln.today AI

7.1 HIGH

MQTT broker typically reachable on LAN/mesh network (AV:A); unauthenticated write to mesh records gives I:H, no data read (C:N), only indirect disruption (A:L).

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L

4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Metadata Corrected

Sep 02, 2026 - 20:40 vuln.today

tag: N A replaced by TOTOLINK

Analysis Generated

Sep 02, 2026 - 20:37 vuln.today

CVSS changed

Sep 02, 2026 - 18:22 NVD

9.8 (CRITICAL)

CVE Published

Sep 01, 2026 - 00:00 cve.org

UNKNOWN (no severity yet)

CVE Published

Sep 01, 2026 - 00:00 cve.org

CRITICAL 9.8

DescriptionCVE.org

Incorrect access control in the recvIndirectMeshInfo function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to insert or replace mesh neighbor records via sending a crafted MQTT message to the cs_broker component.

AnalysisAI

Incorrect access control in the recvIndirectMeshInfo function of the TOTOLINK T6 router (firmware 4.1.5cu.748_B20211015) lets remote unauthenticated attackers insert or replace mesh neighbor records by sending a crafted MQTT message to the cs_broker component. The CVSS 9.8 rating reflects an unauthenticated network-facing vector, but the primary real impact is integrity (poisoning of the mesh neighbor table), with no confidentiality read and only indirect availability effect. …

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Vulnerability AssessmentAI

Exploitation	Exploitation requires network reachability to the TOTOLINK T6's cs_broker MQTT component and the ability to publish a crafted MQTT message to the recvIndirectMeshInfo handler; no authentication, no user interaction, and no special device configuration are needed on affected firmware 4.1.5cu.748_B20211015 (CVSS PR:N/UI:N). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	The supplied CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N, C:H/I:H/A:H = 9.8) signals trivially exploitable, unauthenticated, high-impact - but the signals conflict when weighed together. … 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 at time of analysis; monitor the TOTOLINK download portal (https://www.totolink.net/home/menu/detail/menu_listtpl/download/id/190/ids/36.html) and apply a firmware update newer than 4.1.5cu.748_B20211015 once published. … Detailed patch versions, workarounds, and compensating controls in full report.