CVE-2026-51747
Unauthenticated MQTT access control flaw in TOTOLINK T6 allows forged mesh heartbeats
Is CVE-2026-51747 being exploited?
Not confirmed. CVE-2026-51747 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.44% probability of exploitation in the next 30 days.
How severe is CVE-2026-51747?
CVE-2026-51747 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-51747?
Not known from our data. No patch reference has been recorded for CVE-2026-51747, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-51747 affect?
CVE-2026-51747 affects TOTOLINK T6 (firmware 4.1.5cu.748_B20211015), TOTOLINK routers running same cs_broker MQTT component. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51747?
Isolate affected devices, block MQTT broker access, monitor, apply vendor firmware update when released
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attacker can send crafted MQTT to cs_broker to inject forged mesh heartbeats to master, enabling node impersonation, mesh disruption or DoS.
Immediate action required