CVE-2026-76859 in NR255-V
Summary
by MITRE • 09/16/2026
Netcore NR255-V version 1.5.130703 contains a sensitive information disclosure vulnerability in the user_pass_show.cgi component. Low-privilege attackers can exploit this flaw via ui_config_2.xml and misc.js to disclose router credentials.
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Analysis
by VulDB Data Team • 09/16/2026
The Netcore NR255-V, specifically version 1.5.130703 of its firmware, suffers from a critical sensitive information disclosure vulnerability located within the user_pass_show.cgi component. This flaw represents a significant security deficiency in how the router handles and exposes administrative credentials to end-users interacting with the device's web-based management interface. The vulnerability stems from improper access control mechanisms and insufficient sanitization or encryption practices when rendering configuration data through specific client-side scripts, namely ui_config_2.xml and misc.js. These components are responsible for loading user settings into the browser environment, but in this instance, they inadvertently expose plaintext credentials that should be masked or protected by strict server-side validation checks.
From a technical perspective, the exploitation of this vulnerability does not require authentication as an administrator, which classifies it as accessible to low-privilege attackers. An attacker with network access to the router's management interface can interact directly with the specified CGI endpoint and associated JavaScript files. By manipulating or simply viewing the source code delivered by ui_config_2.xml and misc.js, an adversary can extract stored credentials in clear text. This occurs because the firmware fails to properly obfuscate sensitive fields during the rendering process on the client side. The presence of plaintext passwords within these downloadable resources allows for immediate credential harvesting without the need for complex reverse engineering or memory dumping techniques typically associated with more advanced exploits.
The operational impact of this vulnerability is severe, as it effectively bypasses the primary authentication barrier protecting the router's configuration. Once an attacker obtains valid administrative credentials through this disclosure mechanism, they gain full control over the device. This level of access enables a range of malicious activities including reconfiguring network settings to facilitate man-in-the-middle attacks, redirecting traffic to malicious domains for phishing or malware distribution, and compromising all devices connected to the local area network. Furthermore, if users employ password reuse across other services such as email accounts or banking portals, the exposure of router credentials can lead to broader identity theft and financial loss beyond the immediate scope of the network infrastructure.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-200, which defines Exposure of Sensitive Information to an Unauthorized Actor. It also relates closely to CWE-522, Insufficiently Protected Credentials in Storage or Transmission, as the credentials are exposed via client-side resources that should be treated as sensitive data. In terms of the MITRE ATT&CK framework for IoT and network devices, this behavior corresponds to techniques involving Credential Access through Client-Side Scripting and potentially Information Discovery from Local Network Sources. The lack of proper access controls on the CGI endpoint further reflects issues categorized under CWE-285, Improper Authorization, as low-privilege users are able to perform actions that should be restricted to administrative roles or completely blocked if not authenticated properly.
Mitigation strategies for this vulnerability must focus on both immediate remediation and long-term architectural improvements. The most effective solution is the deployment of a firmware update provided by Netcore that addresses the flaw in user_pass_show.cgi, ensuring that sensitive fields are either removed from client-side responses entirely or rendered as masked characters with no underlying plaintext data exposed to JavaScript objects. If an updated firmware is not immediately available, administrators should restrict access to the router's management interface using firewall rules, allowing only trusted IP addresses to connect via HTTP or HTTPS. Additionally, enabling WPA3 encryption for wireless connections and disabling remote administration features can reduce the attack surface significantly. Users are also advised to change their default administrative passwords regularly and avoid reusing these credentials on other platforms to limit the potential damage if such disclosures occur in future firmware versions.