CVE-2026-51731
Unauthenticated VLAN deletion on TOTOLINK T6 via /cgi-bin/cstecgi.cgi
Is CVE-2026-51731 being exploited?
Not confirmed. CVE-2026-51731 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-2026-51731?
CVE-2026-51731 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-2026-51731?
Not known from our data. No patch reference has been recorded for CVE-2026-51731, 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-2026-51731 affect?
CVE-2026-51731 affects TOTOLINK T6 (firmware 4.1.5cu.748_B20211015), TOTOLINK routers implementing delVlanCfg via /cgi-bin/cstecgi.cgi. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51731?
Isolate affected devices, block admin HTTP access, apply vendor firmware when available.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote removal of VLAN entries via crafted POST, breaking segmentation, exposing traffic, enabling lateral movement or VLAN DoS.
Immediate action required