CVE-2025-50635 in WF2780
Summary
by MITRE • 08/13/2025
A null pointer dereference vulnerability was discovered in Netis WF2780 v2.2.35445. The vulnerability exists in the FUN_0048a728 function of the cgitest.cgi file. Attackers can trigger this vulnerability by controlling the CONTENT_LENGTH variable, causing the program to crash and potentially leading to a denial-of-service (DoS) attack.
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Analysis
by VulDB Data Team • 08/14/2025
The null pointer dereference vulnerability identified as CVE-2025-50635 represents a critical security flaw within the Netis WF2780 router firmware version 2.2.35445. This vulnerability specifically manifests within the cgitest.cgi web interface component, where the FUN_0048a728 function fails to properly validate input parameters before attempting memory access operations. The affected device operates as a network gateway and web server, making it a prime target for remote exploitation. The vulnerability stems from inadequate input sanitization mechanisms that allow attackers to manipulate the CONTENT_LENGTH variable through HTTP requests, bypassing normal validation procedures. This flaw directly aligns with CWE-476 which categorizes null pointer dereference conditions as a common programming error that can lead to application crashes and system instability. The vulnerability exists within the context of web-based administration interfaces where user-provided data is processed without sufficient validation, creating an attack surface that adversaries can exploit to disrupt normal network operations.
The technical implementation of this vulnerability occurs when an attacker crafts a malicious HTTP request that manipulates the CONTENT_LENGTH header parameter to specific values that trigger the function's failure path. During normal operation, the FUN_0048a728 function expects certain data structures to be properly initialized before accessing their memory locations. However, when the CONTENT_LENGTH variable is controlled by an attacker, it can cause the program flow to reach a point where a null pointer is dereferenced, leading to immediate program termination. This behavior follows the typical exploitation pattern for denial-of-service vulnerabilities where the attacker's goal is to disrupt service availability rather than gain unauthorized access to system resources. The vulnerability's impact is amplified by the fact that the affected device serves as a primary network gateway, meaning that successful exploitation can potentially isolate network users from internet connectivity and internal network resources. The attack vector is particularly concerning as it requires no authentication and can be executed remotely through standard web browser interfaces, making it accessible to any attacker with network access to the device.
The operational consequences of this vulnerability extend beyond simple service disruption to potentially compromise network infrastructure reliability and availability. When exploited, the null pointer dereference causes the web server component to crash, forcing administrators to manually restart the service or reboot the entire device. This disruption can occur at any time, potentially during critical network operations or peak usage periods, leading to significant business impact. Network administrators may experience difficulty in maintaining service availability, especially in environments where continuous network access is required for business operations. The vulnerability's presence in a router firmware means that the impact is not limited to a single application but affects the entire network infrastructure that relies on the device for routing and connectivity services. Additionally, this vulnerability can serve as a precursor to more sophisticated attacks, as the DoS condition may be used to create cover for other malicious activities or to test network resilience against similar exploitation techniques. The attack pattern aligns with ATT&CK technique T1499 which describes adversary actions to impair availability of systems and resources, specifically through denial-of-service mechanisms that target network infrastructure components.
Mitigation strategies for this vulnerability should include immediate firmware updates from the manufacturer to address the null pointer dereference in the cgitest.cgi component. Network administrators should implement network segmentation to limit access to administrative interfaces and restrict the attack surface where possible. The implementation of web application firewalls can provide additional protection by filtering malicious CONTENT_LENGTH values before they reach the vulnerable function. Regular network monitoring should be established to detect unusual traffic patterns that might indicate exploitation attempts. System administrators should also consider disabling unnecessary web interfaces and services when they are not actively required for network management. The vulnerability highlights the importance of input validation and proper error handling in embedded systems, particularly those serving as network gateways where reliability is paramount. Organizations should establish robust patch management procedures to ensure timely deployment of security updates. Additionally, implementing network access controls to restrict administrative interface access to trusted IP ranges can significantly reduce the risk of exploitation. The vulnerability serves as a reminder of the critical need for security testing in embedded network devices and the importance of following secure coding practices to prevent null pointer dereference conditions in production environments.