CVE-2026-76868 in NR255-V
Summary
by MITRE • 09/16/2026
Netcore NR255-V version 1.5.130703 contains a null pointer dereference vulnerability in route_policy_add.cgi caused by a missing exit_port parameter. Attackers can send requests lacking the exit_port field to trigger the null pointer dereference, resulting in a denial of service.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/16/2026
The Netcore NR255-V router running firmware version 1.5.130703 is susceptible to a critical input validation flaw within its web management interface, specifically located in the route_policy_add.cgi script. This vulnerability stems from an insufficient check for mandatory parameters during the processing of routing policy configurations. The CGI application expects specific fields to be present in incoming HTTP requests to properly initialize internal data structures and execute subsequent logic operations. However, the implementation fails to verify the existence or validity of the exit_port parameter before attempting to access it within the code execution path. This oversight represents a fundamental failure in defensive programming practices where input sanitization is not rigorously enforced prior to variable dereferencing.
From a technical perspective, this flaw manifests as a null pointer dereference when an attacker crafts and submits a malicious HTTP request that omits the exit_port field entirely or provides it with invalid data that resolves to a null value in memory. When the CGI script attempts to read or manipulate the properties of this uninitialized variable, the underlying C runtime environment cannot resolve the memory address associated with the pointer. Consequently, the operating system interrupts the process execution by sending a segmentation fault signal to the application thread handling the request. This abrupt termination causes the web server component hosting the CGI scripts to crash or become unresponsive until it is manually restarted or times out and recovers automatically depending on the specific daemon configuration.
The operational impact of this vulnerability is primarily characterized as a denial of service against the device's administrative interface rather than remote code execution or data exfiltration. By repeatedly sending requests lacking the required exit_port parameter, an attacker can exhaust system resources such as CPU cycles during crash recovery and memory allocation attempts for new request handling threads. This sustained abuse leads to significant latency in legitimate management operations, potential loss of configuration changes due to interrupted processes, and complete unavailability of the router's web-based administration panel. While this does not directly compromise confidentiality or integrity of stored data, it severely degrades availability which is a core component of security triads especially for network infrastructure devices that require consistent administrative access for maintenance and troubleshooting.
This vulnerability aligns with CWE-476 which describes null pointer dereference errors resulting from improper handling of pointers that have not been properly initialized or validated against expected input constraints. In the context of attack frameworks, this behavior corresponds to ATT&CK technique T1595.002 known as Active Scanning where adversaries probe for vulnerabilities by sending malformed requests to identify weaknesses in application logic and server configurations before launching more destructive exploits. The lack of robust parameter validation highlights a common weakness in embedded device firmware development where resource constraints often lead developers to skip comprehensive input checks that are standard in enterprise-grade software applications.
Mitigation strategies should focus on implementing strict input validation at the earliest possible stage within the CGI script execution lifecycle. Developers must ensure that all mandatory parameters including exit_port are explicitly checked for presence and validity before any memory operations or function calls dependent on those values occur. If a required parameter is missing, the application should return an appropriate HTTP error code such as 400 Bad Request rather than proceeding with undefined behavior. Additionally deploying web application firewalls can provide temporary protection by filtering out requests that do not conform to expected schema definitions for routing policy updates until a firmware patch addressing this root cause is released and applied by network administrators.