CVE-2026-51690
Unauthenticated access-control flaw in TOTOLINK T6 allows altering WAN settings via crafted POST
Is CVE-2026-51690 being exploited?
Not confirmed. CVE-2026-51690 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 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-51690?
CVE-2026-51690 is rated Critical with a CVSS score of 9.1. 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-2026-51690?
Not known from our data. No patch reference has been recorded for CVE-2026-51690, 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-2026-51690 affect?
CVE-2026-51690 affects TOTOLINK T6 firmware 4.1.5cu.748_B20211015, TOTOLINK routers exposing setWanCfg endpoint, /cgi-bin/cstecgi.cgi (WAN config). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51690?
Isolate affected devices; block remote admin from WAN; restrict access; apply vendor firmware when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attackers can modify WAN provisioning/connectivity via POST to /cgi-bin/cstecgi.cgi, causing outages, traffic interception, or persistent access.
Immediate action required