CVE-2026-7193: Dbit T-CPE301K Router Auth Bypass Vulnerability

CVE-2026-7193 Overview

CVE-2026-7193 is a hardcoded credentials vulnerability [CWE-798] in the Shenzhen Dbit T-CPE301K 4G WiFi mini-router. The device ships with predefined static credentials on the Telnet service exposed on TCP port 23. An attacker connected to the same network can authenticate with these known credentials and obtain full root access to the router. Successful exploitation compromises the confidentiality, integrity, and availability of the device and any traffic routed through it. The vulnerability was published to the National Vulnerability Database (NVD) on 2026-09-29 and referenced in an INCIBE security notice covering multiple issues in the T-CPE301K product line.

Critical Impact
Any network-adjacent attacker can gain persistent root shell access to the router using publicly known static credentials, enabling traffic interception, pivoting, and firmware tampering.

Affected Products

Shenzhen Dbit T-CPE301K 4G WiFi mini-router
Telnet management service listening on TCP port 23
Firmware versions shipping with the predefined root credentials (see vendor advisory)

Discovery Timeline

2026-09-29 - CVE-2026-7193 published to NVD
2026-09-29 - Last updated in NVD database

Technical Details for CVE-2026-7193

Vulnerability Analysis

The T-CPE301K exposes a Telnet daemon on TCP port 23 that authenticates against a hardcoded account baked into the firmware image. Because the credentials are identical across all deployed units, knowledge of a single working pair is sufficient to authenticate against every device of the same model. Telnet transmits the authentication exchange in cleartext, which further exposes the credentials to any adversary positioned to observe traffic on the local segment. Once authenticated, the attacker receives an interactive root shell with unrestricted access to the underlying Linux userland.

Root access on a customer-premises router enables DNS hijacking, TLS interception through installed CA modification, credential harvesting from LAN clients, and permanent implantation of malicious firmware. The device can also be enrolled into botnets for distributed denial-of-service or proxy abuse.

Root Cause

The root cause is the presence of static, factory-provisioned credentials within the firmware that cannot be rotated or disabled by the end user through the normal administrative interface. This design pattern is catalogued as CWE-798 (Use of Hard-coded Credentials).

Attack Vector

Exploitation requires network reachability to TCP port 23 on the router. In the default deployment, the Telnet service is reachable from any host on the LAN or Wi-Fi segment. An attacker on the same Layer 2 network establishes a Telnet session, submits the known credential pair, and receives a root shell. No user interaction on the victim side is required, and no memory-corruption primitives are needed. Refer to the INCIBE Security Notice for the vendor-coordinated technical details.

Detection Methods for CVE-2026-7193

Indicators of Compromise

Successful Telnet logins to the router on TCP port 23 from LAN clients that do not normally administer network equipment
New or modified /etc/passwd, /etc/shadow, or startup scripts on the device following unexpected reboots
Unexpected outbound connections from the router itself to unknown IP addresses or non-standard ports

Detection Strategies

Perform authenticated and unauthenticated network scans that flag any device listening on TCP port 23, then attempt Telnet banner grabs to fingerprint the T-CPE301K firmware
Correlate DHCP lease logs with observed Telnet sessions to identify unauthorized administrative access
Inspect DNS resolver settings pushed by the router to detect tampering consistent with post-exploitation activity

Monitoring Recommendations

Enable NetFlow or IPFIX on upstream switches and alert on any traffic destined for TCP/23 within the internal network
Collect syslog or packet captures from LAN segments hosting the router and forward them to a centralized SIEM or data lake for retention and analysis
Baseline the router's outbound traffic profile and alert on deviations that suggest command-and-control activity

How to Mitigate CVE-2026-7193

Immediate Actions Required

Disconnect exposed T-CPE301K units from untrusted networks until the Telnet service can be blocked or the firmware updated
Segment the router onto a dedicated management VLAN and restrict administrative access with switch-level ACLs
Rotate any credentials, Wi-Fi PSKs, or shared secrets that may have transited the device while it was reachable via Telnet

Patch Information

No vendor patch is referenced in the NVD entry at the time of publication. Consult the INCIBE Security Notice for the most current remediation guidance from Shenzhen Dbit. Where a firmware update becomes available, apply it and verify that the hardcoded account has been removed rather than simply renamed.

Workarounds

Block inbound connections to TCP port 23 at the network perimeter and on any intermediate firewall
Where the router firmware permits, disable the Telnet daemon entirely and enforce SSH with per-device credentials
Replace affected devices with alternatives that do not embed static administrative credentials when a firmware fix is not forthcoming

bash

# Example: block Telnet on an upstream Linux gateway protecting the router segment
iptables -A FORWARD -p tcp --dport 23 -j DROP
iptables -A INPUT   -p tcp --dport 23 -j DROP