CVE-2018-4063 in AirLink ES450
Summary
by MITRE
An exploitable remote code execution vulnerability exists in the upload.cgi functionality of Sierra Wireless AirLink ES450 FW 4.9.3. A specially crafted HTTP request can upload a file, resulting in executable code being uploaded, and routable, to the webserver. An attacker can make an authenticated HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/12/2025
The vulnerability identified as CVE-2018-4063 represents a critical remote code execution flaw within the Sierra Wireless AirLink ES450 firmware version 4.9.3. This issue resides in the upload.cgi component which handles file upload operations through HTTP requests. The vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly restrict file types and content, allowing malicious actors to bypass security controls and upload arbitrary files to the affected device. The affected system operates as a network communication device that typically serves as a gateway for cellular connectivity in industrial and enterprise environments, making it a prime target for attackers seeking persistent access to critical infrastructure networks.
The technical exploitation of this vulnerability occurs through a specifically crafted HTTP request that leverages the upload.cgi functionality to process and store malicious files on the web server. When an authenticated user submits such a request, the system fails to validate the uploaded file's content, type, or execution permissions, enabling attackers to upload executable code that can be executed by the web server. This flaw allows for the deployment of web shells, backdoors, or other malicious payloads that can provide attackers with persistent access to the device and potentially the broader network it connects to. The vulnerability operates at the application layer and can be triggered through standard HTTP protocols, making it accessible to attackers with minimal specialized tools or knowledge.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass significant risks for network security and infrastructure integrity. Attackers who successfully exploit this vulnerability can establish persistent access points within the network, potentially enabling them to monitor traffic, redirect connections, or use the device as a pivot point for attacking other systems. The affected AirLink ES450 devices typically operate in critical infrastructure environments where they provide essential connectivity services, meaning that exploitation could result in service disruption, data exfiltration, or unauthorized access to sensitive network segments. This vulnerability particularly impacts industrial control systems and enterprise networks that rely on cellular connectivity solutions for remote management and monitoring.
Security mitigations for CVE-2018-4063 should focus on immediate firmware updates from Sierra Wireless to address the underlying validation flaws in the upload.cgi functionality. Organizations should implement network segmentation to limit access to these devices, enforce strict authentication controls, and monitor for suspicious upload activities through network traffic analysis. The vulnerability aligns with CWE-434 which describes insecure file upload vulnerabilities, and represents a clear path for attackers to achieve initial access through the attack chain outlined in MITRE ATT&CK framework under T1190 for exploit public-facing application. Additional defensive measures include implementing web application firewalls, restricting file upload capabilities to essential functions only, and conducting regular security assessments of networked devices to identify similar vulnerabilities in other firmware components.