CVE-2026-114575 in A950RG
Summary
by MITRE • 10/22/2026
A flaw has been found in TOTOLINK A950RG 4.1.2cu.5268_B20221104. Affected by this issue is the function UploadCustomModule of the file lib/cste_modules/product.so. Executing a manipulation of the argument FileMd5 can lead to command injection. The attack can be launched remotely. The exploit has been published and may be used.
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Analysis
by VulDB Data Team • 10/22/2026
The vulnerability identified in TOTOLINK A950RG firmware version 4.1.2cu.5268_B20221104 represents a critical security flaw within the device's administrative interface, specifically located in the UploadCustomModule function found within the lib/cste_modules/product.so library. This component is responsible for handling custom module uploads, a feature often used by administrators to extend router functionality or apply specific configurations. The core technical deficiency lies in the improper validation and sanitization of the FileMd5 argument passed during this upload process. When an attacker provides manipulated input for this parameter, the system fails to adequately filter out malicious shell metacharacters or command sequences before passing them to underlying operating system commands. This lack of rigorous input validation allows an adversary to inject arbitrary Linux commands into the execution context of the vulnerable application, effectively bypassing intended security controls and gaining unauthorized access to the device's internal processes.
From a classification perspective, this vulnerability aligns with CWE-78, which denotes Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection. The flaw is further contextualized within the MITRE ATT&CK framework under technique T1059, specifically sub-technique 004 for Unix Shell Commands, indicating that successful exploitation allows an attacker to execute commands directly on the target operating system shell. Because this function is accessible via the web-based management interface and does not require prior authentication in certain configurations or can be triggered by authenticated users with limited privileges depending on specific implementation details of the upload mechanism, it presents a significant remote attack vector. The fact that public exploits have been published significantly lowers the barrier to entry for malicious actors, enabling automated scanning tools and opportunistic attackers to compromise devices connected to the internet without needing sophisticated custom tooling.
The operational impact of this vulnerability is severe, as successful exploitation grants an attacker full command-line access to the router's underlying Linux environment. This level of control allows for a wide range of destructive actions beyond simple data exfiltration. An adversary can modify system configurations, install persistent backdoors or malware such as botnet clients like Mirai variants, redirect network traffic through man-in-the-middle attacks, or use the compromised device as a pivot point to attack other systems on the local network segment. Given that routers often serve as the primary gateway for home and small business networks, compromising this single device can lead to widespread disruption of internet connectivity, privacy violations for all connected devices, and potential lateral movement into more sensitive internal infrastructure. The remote nature of the exploit means that physical access is not required, making it particularly dangerous in environments where routers are deployed without immediate visibility or monitoring.
Mitigation strategies must prioritize both immediate remediation and long-term security hygiene. The most effective solution is to update the TOTOLINK A950RG firmware to a version released after this vulnerability was disclosed, ensuring that the developers have implemented proper input sanitization for the FileMd5 parameter in the UploadCustomModule function. If an official patch is unavailable or delayed, administrators should disable remote management features entirely and restrict access to the router's web interface to trusted local network segments only. Additionally, implementing strict firewall rules to block inbound traffic on ports associated with the administrative interface from untrusted networks can reduce the attack surface. Network segmentation is also recommended to isolate IoT devices like routers from critical internal systems, limiting the potential blast radius of a successful compromise. Regular monitoring for unusual outbound connections or high CPU usage can help detect exploitation attempts early, although proactive patching remains the primary defense against this class of command injection vulnerabilities.