CVE-2026-51625: TOTOLINK T6 Information Disclosure Flaw

CVE-2026-51625 Overview

CVE-2026-51625 is an incorrect access control vulnerability in the getWiFiEasyCfg function of the TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015. Unauthenticated attackers can send a crafted POST request to /cgi-bin/cstecgi.cgi to retrieve sensitive wireless configuration data. Exposed information includes Service Set Identifiers (SSIDs) and Wi-Fi keys. The flaw is categorized under [CWE-284: Improper Access Control] and is remotely exploitable over the network without user interaction.

Critical Impact
Unauthenticated remote attackers can extract Wi-Fi credentials from affected TOTOLINK T6 routers, enabling wireless network compromise and downstream lateral movement.

Affected Products

TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015
Devices exposing the /cgi-bin/cstecgi.cgi management endpoint
Deployments using the vulnerable getWiFiEasyCfg handler

Discovery Timeline

2026-08-28 - CVE-2026-51625 published to NVD
2026-09-01 - Last updated in NVD database

Technical Details for CVE-2026-51625

Vulnerability Analysis

The vulnerability exists in the getWiFiEasyCfg handler exposed through the Common Gateway Interface (CGI) endpoint /cgi-bin/cstecgi.cgi. This handler returns wireless configuration data including SSIDs and pre-shared keys. The handler fails to enforce authentication or session validation before responding.

An attacker who can reach the device HTTP interface issues a crafted POST request invoking the getWiFiEasyCfg action. The router responds with sensitive Wi-Fi configuration without verifying the requester's identity. This information disclosure enables attackers to join the target wireless network and pivot to internal hosts.

The attack requires no privileges and no user interaction, and it targets confidentiality only. Integrity and availability are not directly impacted by the disclosure primitive itself.

Root Cause

The root cause is missing authorization on a sensitive management endpoint. The getWiFiEasyCfg function does not check whether the caller possesses a valid administrative session token before returning wireless credentials. This deviates from the least-privilege principle and violates [CWE-284].

Attack Vector

Exploitation requires network reachability to the router's web management interface. An attacker sends an HTTP POST request to /cgi-bin/cstecgi.cgi with a JSON body invoking the getWiFiEasyCfg topic. Because no realCodeExamples are available for this CVE, refer to the GitHub CVE Coordination Repo for reproduction details.

Devices exposing the management interface to the wide-area network (WAN) are directly reachable from the internet. On local networks, any attacker with Layer 2 access can extract credentials from a nearby router.

Detection Methods for CVE-2026-51625

Indicators of Compromise

Unexpected POST requests to /cgi-bin/cstecgi.cgi from unknown source addresses in router HTTP logs
Request bodies containing the getWiFiEasyCfg topic or method identifier
HTTP 200 responses returning wireless configuration payloads to unauthenticated clients
New or unrecognized wireless clients appearing on the network shortly after suspicious CGI requests

Detection Strategies

Monitor router web access logs for requests to /cgi-bin/cstecgi.cgi that lack a valid administrative session cookie.
Alert on POST requests to the router management interface originating from WAN-side IP addresses.
Correlate CGI endpoint access with subsequent new device associations on the wireless network.

Monitoring Recommendations

Forward router syslog data to a centralized logging platform and alert on anomalous administrative endpoint access.
Baseline expected sources of management traffic and flag deviations for review.
Track wireless client join events for previously unseen MAC addresses following management interface access.

How to Mitigate CVE-2026-51625

Immediate Actions Required

Disable remote (WAN-side) administration on affected TOTOLINK T6 devices to eliminate internet-based exposure.
Restrict local administrative access to a trusted management VLAN or specific management hosts.
Rotate all Wi-Fi pre-shared keys and SSIDs if the device may have been queried by an untrusted party.
Check the TOTOLINK Firmware Download Page for updated firmware.

Patch Information

At the time of publication, no vendor-confirmed patched firmware version is listed in the NVD entry for CVE-2026-51625. Consult the TOTOLINK Official Website and the GitHub CVE Coordination Repo for coordination status and any subsequent firmware release addressing the getWiFiEasyCfg authorization gap.

Workarounds

Block inbound access to TCP ports serving the router web interface at the perimeter firewall.
Place the router management interface behind a network access control list that permits only administrative hosts.
Segment the wireless network from sensitive internal resources so credential disclosure does not immediately grant lateral access.
Replace end-of-support hardware with vendor-supported models that receive security updates.

bash

# Example: block WAN access to the router management interface using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -i <wan_iface> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -i <wan_iface> -j DROP