CVE-2026-76853 in NR268
Summary
by MITRE • 09/16/2026
Netcore NR268 firmware version 1.7.121109 contains a security check bypass vulnerability in the parame_put_file.cgi restore archive prefix validation. Attackers can exploit the flawed prefix check in put_parame_file_cgi.c to bypass restricted restore archive handling.
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Analysis
by VulDB Data Team • 09/16/2026
The Netcore NR268 router, specifically firmware version 1.7.121109, contains a critical security flaw within its web management interface that allows for the unauthorized restoration of configuration archives. This vulnerability resides in the parame_put_file.cgi script, which is responsible for handling file uploads and subsequent system restore operations. The core issue stems from an insufficient validation mechanism applied to the archive prefix during the upload process. In secure systems, such prefixes are typically used as a safety measure to ensure that only authorized or expected types of configuration files can be processed by the restoration routine, thereby preventing attackers from injecting malicious payloads disguised as legitimate backup data.
The technical flaw involves a bypass in the prefix validation logic within the put_parame_file_cgi.c source file. When an attacker uploads a restore archive, the system is supposed to verify that the filename or internal structure adheres to strict naming conventions or prefixes defined by the manufacturer. However, due to improper input sanitization and lack of rigorous boundary checks, the application fails to correctly enforce these restrictions. This oversight allows malicious actors to manipulate the file parameters so that they appear valid during the initial check but are subsequently processed in a way that bypasses the intended security controls. Consequently, an attacker can upload arbitrary files or configurations that would normally be rejected by the system's integrity checks.
The operational impact of this vulnerability is severe, as it effectively grants remote attackers the ability to overwrite critical router configuration files without proper authentication or authorization constraints related to file type validation. By exploiting this flaw, an adversary could restore a maliciously crafted archive containing backdoors, altered DNS settings, compromised administrative credentials, or other persistent threats. This compromises the confidentiality, integrity, and availability of the network infrastructure managed by the device. Furthermore, since routers often serve as gateways for entire local networks, compromising one such device can lead to broader network infiltration, man-in-the-middle attacks, or use of the router in botnet activities.
This vulnerability aligns with CWE-20 Improper Input Validation and CWE-732 Incorrect Permission Assignment for Critical Resource, reflecting a failure to properly restrict access to sensitive system functions based on input characteristics. From an offensive security perspective, this behavior is consistent with ATT&CK technique T1505.003 Server Software Component: Web Shell, as the ability to upload and execute arbitrary configuration files can facilitate persistent remote access. To mitigate this risk, users should immediately update their Netcore NR268 firmware to a patched version that addresses the input validation logic in the CGI scripts. Additionally, administrators should restrict management interface access to trusted IP addresses only and monitor for unusual file upload activities or unexpected changes in router configuration files as an indicator of compromise.