CVE-2026-7193

Executive Summary

CVE-2026-7193 is a use-of-hardcoded-credentials vulnerability (CWE-798) in the Dbit T-CPE301K 4G WiFi mini-router. The device ships with static credentials for its Telnet service on port 23, allowing any attacker with network adjacency to authenticate and obtain full root access. No patch, public PoC, or exploit code is currently available, and the device is unpatched as of this report.

Technical Analysis

The vulnerability class is CWE-798: Use of Hard-coded Credentials. The affected product is the Dbit T-CPE301K 4G WiFi mini-router. According to the NVD description, the device exposes a Telnet service on TCP port 23 that authenticates against predefined (static) credentials. Because these credentials are fixed at manufacture or firmware build time and cannot be changed by the end user, any actor who can reach the Telnet service on the local network segment can authenticate successfully.

The attack surface is the Telnet management interface bound to port 23. Network adjacency is the primary precondition: the attacker must be "connected to the same network" as the device, per the description. This is consistent with the CVSS vector AV:A (Adjacent Network), which reflects that the vulnerability is exploitable from the same Layer 2/Layer 3 broadcast domain, not across the public internet by default.

Once authenticated over Telnet, the vulnerability results in "full root access to the device." This implies the Telnet service grants a privileged shell with root-level permissions rather than a restricted management CLI. Root access on a router provides complete control over device configuration, network traffic handling, and — depending on firmware capabilities — the ability to persist malware, intercept traffic, or pivot to connected hosts.

No specific function names, binaries, credential values, or firmware file paths are disclosed in the NVD description or CNA title. Accordingly, this report describes the vulnerability at the class level and does not fabricate implementation-specific details. The precise static credential string, Telnet daemon implementation, and firmware version range are not available from the provided data.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (CWE-798, hard-coded credentials) and the information in the NVD description.

1. Reconnaissance / target identification. An attacker on the same network segment as the Dbit T-CPE301K scans for hosts exposing TCP port 23. Tools such as Nmap (nmap -p 23 <subnet>) or mass network scanning would identify responsive Telnet services. Device fingerprinting via the responding banner or HTTP management interface (if present on the same host) would confirm the model as T-CPE301K.

2. Triggering the flaw class. The attacker initiates a Telnet session to port 23 and supplies the predefined credentials. Because credentials are static and hard-coded (CWE-798), no brute-forcing is strictly required if the credential values are known or documented; repeated guessing is also viable given the lack of account lockout information. Successful authentication is the exploitation event.

3. Payload / execution method at the class level. Upon successful Telnet authentication, the service presents a shell with root privileges, per the NVD description ("gain full root access to the device"). The attacker then issues commands through that shell. No specific command payload is described in the source data, so no specific execution payload is presented here.

4. Post-exploitation impact. With root access, the attacker can modify router configuration, alter DNS settings, redirect or intercept traffic, disable logging, install persistent backdoors, or use the device as a pivot point into the local network. Full root control also enables firmware modification or credential manipulation to maintain access across reboots.

Impact Assessment

The impact is rated High across Confidentiality, Integrity, and Availability based on the NVD description of "full root access." No CVSS score or vector was assigned by NVD; the vector shown in METADATA (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) is an analyst-derived estimate consistent with an adjacent-network, no-privilege, no-user-interaction attack yielding root control, and should not be treated as an official score.

Business impact: A compromised edge router provides an adversary a foothold at the network perimeter/interior boundary. Because the T-CPE301K is a 4G WiFi mini-router, affected deployments are likely small-office, branch, IoT gateway, or mobile/hotspot environments. The blast radius extends to all hosts behind the router, which may have their traffic intercepted, redirected, or blocked. Root access also permits the device to be enrolled into a botnet or used as a persistent network implant.

Affected systems: Dbit T-CPE301K 4G WiFi mini-routers. No affected version range is published, implying all firmware versions may be impacted unless a vendor fix is released. No CISA KEV listing and no EPSS score (not yet scored by FIRST.org) are available — absence of these signals does not imply low risk, only that formal scoring/tracking has not occurred.

Detection Guidance

Sigma Rule

title: Telnet Authentication to Dbit T-CPE301K Router (Hardcoded Credential Abuse)
id: 7f3a9c1e-4b2d-4e8a-9c6f-1a2b3c4d5e6f
status: experimental
description: Detects inbound Telnet (TCP/23) authentication attempts targeting Dbit T-CPE301K devices, consistent with exploitation of hard-coded credentials (CVE-2026-7193).
references:
  - https://nvd.nist.gov/vuln/detail/CVE-2026-7193
author: valtersit.com
date: 2026/01/01
tags:
  - attack.t1078.001
  - attack.initial_access
logsource:
  category: network_connection
  product: firewall
detection:
  selection_port:
    dst_port: 23
  selection_action:
    action: 'allow'
  condition: selection_port and selection_action
falsepositives:
  - Legitimate administrative Telnet sessions (Telnet should not be used; treat as suspicious)
level: high

YARA Rule

rule CVE_2026_7193_Hardcoded_Credentials_Strings
{
    meta:
        description = "Detects firmware strings referencing Telnet service and hardcoded credential artifacts associated with Dbit T-CPE301K (CVE-2026-7193)"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-7193"
        date = "2026-01-01"
        severity = "high"

    strings:
        $telnet = "telnetd" ascii nocase
        $port   = "23" ascii
        $model  = "T-CPE301K" ascii nocase

    condition:
        uint16(0) == 0x5A4D or $model or ($telnet and $port)
}

Suricata IDS Rule

alert tcp any any -> any 23 (msg:"CVE-2026-7193 Dbit T-CPE301K Telnet hardcoded credential access attempt"; flow:to_server,established; content:"|FF FD|"; depth:3; classtype:attempted-admin; sid:20267193; rev:1; reference:cve,2026-7193; metadata:affected_product "Dbit T-CPE301K", attack_target "Network_Device", created_at "2026_01_01";)

Elastic Detection

network where network.transport == "tcp" and destination.port == 23 and event.action == "connection_accepted"

Splunk SPL Query

index=firewall OR index=netflow action=allowed dest_port=23
| stats count values(src_ip) as sources values(dest_ip) as targets by dest_ip
| where count > 0
| table dest_ip targets sources count

Wazuh OSSEC Rule

<group name="cve-2026-7193,telnet,router,">
  <rule id="100193" level="12">
    <decoded_as>json</decoded_as>
    <field name="dst_port">^23$</field>
    <description>CVE-2026-7193: Telnet (port 23) session to Dbit T-CPE301K mini-router - possible hardcoded credential exploitation.</description>
    <mitre>
      <id>T1078.001</id>
    </mitre>
    <group>cve_2026_7193,network_device,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix, affected version list, or workaround is available from tracked sources.

1. Immediate mitigations:

   • Disable the Telnet service on TCP port 23. If the device UI does not permit disabling Telnet, isolate the device on a dedicated management VLAN and block inbound TCP/23 from all untrusted segments and from client networks.
   • Enforce network segmentation so that no untrusted or guest hosts share a broadcast domain with the router's management interface (the attack requires network adjacency).
   • Restrict port 23 at the firewall/Wi-Fi access layer to trusted administrative endpoints only.
   • If the static Telnet credentials can be changed via the device CLI/UI, change them immediately; do not assume they are unique per unit.
   • Monitor for suspicious Telnet sessions and root-level configuration changes.

2. Patch/upgrade steps:

   • No patch is available. Contact Dbit support for firmware status on the T-CPE301K and monitor for a vendor advisory. No fixed version is currently identified.
   • If a vendor fix is later released, validate the firmware version, back up the configuration, and apply the update per vendor instructions.

3. Long-term hardening:

   • Remove Telnet entirely in favor of SSH or an authenticated web management interface where supported.
   • Eliminate hard-coded credentials as a design pattern; enforce unique per-device credentials provisioned at manufacture or first boot, with mandatory change on first login.
   • Implement firmware integrity verification and secure boot.
   • Maintain an inventory of edge/router devices and audit for default/static credentials on a recurring schedule.
   • For environments that cannot mitigate, replace the affected hardware with a device that supports secure remote management.

References

1. NVD — CVE-2026-7193: https://nvd.nist.gov/vuln/detail/CVE-2026-7193
2. MITRE CWE-798 — Use of Hard-coded Credentials: https://cwe.mitre.org/data/definitions/798.html
3. MITRE ATT&CK T1078.001 — Valid Accounts: Default Accounts: https://attack.mitre.org/techniques/T1078/001/
4. CISA Known Exploited Vulnerabilities Catalog (CVE-2026-7193 not listed as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
5. FIRST EPSS (CVE-2026-7193 not yet scored): https://www.first.org/epss/

No known threat actor campaigns or exploit-in-the-wild evidence are available for this CVE at the time of writing. No public PoC or Nuclei template exists.