CVE-2026-51757
Unauthenticated MQTT trigger allows firmware flash on TOTOLINK T6 routers.
Is CVE-2026-51757 being exploited?
Not confirmed. CVE-2026-51757 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-2026-51757?
CVE-2026-51757 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-2026-51757?
Not known from our data. No patch reference has been recorded for CVE-2026-51757, 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-2026-51757 affect?
CVE-2026-51757 affects TOTOLINK T6 (firmware 4.1.5cu.748_B20211015), TOTOLINK routers using cs_broker MQTT component. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51757?
Isolate affected devices, block MQTT ports, restrict management access, 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 to cs_broker to start firmware download/flash, enabling remote firmware install, persistent compromise or device bricking.
Immediate action required