Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-51717 – Unauthenticated Operating Mode Change – TOTOLINK T6 4.1.5cu.748_B20211015

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-51717 is an incorrect access control vulnerability in the setOpModeCfg function of the TOTOLINK T6 router, firmware version 4.1.5cu.748_B20211015. The flaw allows an unauthenticated remote attacker to send a crafted POST request to the device’s /cgi-bin/cstecgi.cgi endpoint and change the router’s operating mode without providing any credentials. It carries a CVSS v3.1 base score of 9.1 (Critical).

Technical details

  • Root cause: the setOpModeCfg function exposed via /cgi-bin/cstecgi.cgi fails to enforce authentication before processing operating-mode configuration requests (CWE-284, Improper Access Control).
  • Trigger conditions: an attacker sends a specially crafted HTTP POST request to /cgi-bin/cstecgi.cgi invoking the setOpModeCfg action; no valid session or credentials are required.
  • Attack vector: remote, over the network, against the device’s exposed web management interface; no user interaction is needed.
  • Impact: unauthenticated attackers can change the device’s operating mode (e.g., router/AP/repeater/bridge mode), which can disrupt network connectivity or be used to reconfigure the device as part of a broader attack chain.

Affected software

  • TOTOLINK T6, firmware version 4.1.5cu.748_B20211015

Severity

  • CVSS v3.1 Base Score: 9.1 (Critical)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Mitigation and recommended actions

  • Immediate: no vendor-published fixed firmware version has been identified for this issue at time of writing. Check the TOTOLINK support/download portal for the T6 model regularly for an updated firmware release addressing this CVE and apply it as soon as it becomes available.
  • If no patch: restrict access to the device’s web management interface so it is not reachable from the public internet; place the router’s admin interface behind a trusted management network or VPN, and disable remote/WAN management if enabled. Monitor for unexpected changes to the device’s operating mode as an indicator of exploitation attempts.

How IONIX identifies potentially affected assets

IONIX matches the following signals against data already collected when it crawled the asset; identifying the technology sends no request beyond that crawl.

  • Raw response body: /cgi-bin/cstecgi.cgi, TOTOLINK

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge