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PatchSiren cyber security CVE debrief

CVE-2026-51767 TOTOLINK CVE debrief

The CVE-2026-51767 vulnerability affects TOTOLINK T6 devices with firmware version 4.1.5cu.748_B20211015. This critical vulnerability, with a CVSS score of 9.8, allows unauthenticated attackers to reset pairing state and reboot the device via crafted MQTT messages to the cs_broker component. Users and administrators should be aware of the vulnerability's impact on their systems and take immediate action to patch or mitigate the issue. The vulnerability's severity and potential operational impact necessitate prompt attention.

Vendor
TOTOLINK
Product
T6
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-01
Original CVE updated
2026-09-03
Advisory published
2026-09-01
Advisory updated
2026-09-03

Who should care

Users and administrators of TOTOLINK T6 devices, particularly those using version 4.1.5cu.748_B20211015, should be aware of this critical vulnerability and take immediate action to patch or mitigate the issue. The vulnerability's high severity and potential impact on device security and availability necessitate prompt attention from operators, administrators, and security teams. Affected organizations should review their deployments, assess potential exposure, and implement recommended mitigations or patches to prevent exploitation.

Technical summary

The recvClearPairCfg function in TOTOLINK T6 4.1.5cu.748_B20211015 is vulnerable to unauthenticated attacks, allowing attackers to reset pairing state and reboot the device via crafted MQTT messages to the cs_broker component. This issue has a CVSS score of 9.8 and is classified as CRITICAL. The vulnerability affects the device's access control mechanism, enabling attackers to manipulate the pairing state and cause a device reboot. Users and administrators must prioritize patching or mitigating this vulnerability to prevent potential exploitation.

Defensive priority

TOTOLINK T6 devices are vulnerable to a critical access control issue; immediate patching is recommended.

Recommended defensive actions

  • Apply patches or updates provided by the vendor
  • Restrict access to the cs_broker component
  • Monitor MQTT traffic for suspicious activity
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The recvClearPairCfg function in TOTOLINK T6 4.1.5cu.748_B20211015 is vulnerable to unauthenticated attacks, allowing attackers to reset pairing state and reboot the device via crafted MQTT messages to the cs_broker component. Evidence is limited; further verification is needed.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-51767 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-51767

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-51767 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-51767

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.