CVE-2026-51691
Unauthenticated access-control flaw in TOTOLINK T6 allows firmware upload/flash via crafted POST.
Is CVE-2026-51691 being exploited?
Not confirmed. CVE-2026-51691 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-2026-51691?
CVE-2026-51691 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-2026-51691?
Yes. A fix has been recorded for CVE-2026-51691. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-51691 affect?
CVE-2026-51691 affects TOTOLINK T6 firmware 4.1.5cu.748_B20211015. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-51691?
Apply vendor firmware update; restrict admin access and block /cgi-bin/cstecgi.cgi.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attackers can upload/flash firmware via /cgi-bin/cstecgi.cgi, enabling remote code execution, persistent device takeover and network compromise.
Immediate action required