CVE-2026-51764
Unauthenticated MQTT message can overwrite cloud-tracking files on TOTOLINK T6
Is CVE-2026-51764 being exploited?
Not confirmed. CVE-2026-51764 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-2026-51764?
CVE-2026-51764 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-2026-51764?
Not known from our data. No patch reference has been recorded for CVE-2026-51764, 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-2026-51764 affect?
CVE-2026-51764 affects TOTOLINK T6 (firmware 4.1.5cu.748_B20211015), TOTOLINK routers running vulnerable firmware, cs_broker MQTT component. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51764?
Isolate devices from MQTT access, block MQTT ports, disable cloud features, apply vendor firmware when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attacker can send crafted MQTT messages to cs_broker to overwrite cloud-result files, enabling data tampering, service disruption, and persistent compromise.
Immediate action required