CVE-2026-71914 in VigorAP 918R
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorAP models contain a command injection vulnerability in the dray_apm component. The vulnerability is caused by insufficient validation of UDP message content after START_SPEED_TEST before command execution. A remote attacker can trigger this vulnerability via a crafted message to execute arbitrary commands with root privileges.
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Analysis
by VulDB Data Team • 08/24/2026
The identified security flaw resides within the DrayTek VigorAP series, specifically affecting the dray_apm component which is responsible for managing access point operations and performance monitoring functions. This critical vulnerability manifests as an OS command injection weakness stemming from a fundamental failure in input validation mechanisms. The root cause lies in how the system processes UDP messages that initiate speed tests. Specifically, after receiving a START_SPEED_TEST instruction, the application fails to adequately sanitize or validate the content of subsequent data packets before passing them into shell commands for execution. This lack of rigorous boundary checking allows malicious actors to inject arbitrary operating system commands directly into the processing pipeline, bypassing intended security controls and leveraging the high-privilege context in which the dray_apm service typically operates.
From a technical perspective, this vulnerability exploits the trust relationship between network management interfaces and underlying system utilities. When an attacker sends a specially crafted UDP packet containing malicious payload data immediately following or associated with a START_SPEED_TEST command, the vulnerable component interprets parts of that payload as executable shell instructions rather than mere test parameters. Because the dray_apm process often runs with elevated privileges to perform network diagnostics and configuration changes, any successfully injected commands are executed with root-level access on the affected device. This architectural design choice significantly amplifies the severity of the flaw, transforming a simple input validation error into a full system compromise vector that does not require authentication if the service is exposed or accessible within the local network segment without proper isolation.
The operational impact of this vulnerability is severe and multifaceted. A remote attacker can achieve complete control over the compromised access point by executing arbitrary commands with root privileges. This capability allows for extensive reconnaissance, persistence establishment through backdoors or modified startup scripts, lateral movement to other devices on the internal network, and potential disruption of critical network services. Furthermore, since these are wireless access points often positioned at the edge of corporate networks, a successful exploitation could serve as an initial entry point for broader attacks against sensitive data stores, IoT device ecosystems, or industrial control systems connected via the same infrastructure. The ability to execute commands remotely without authentication makes this particularly dangerous in environments where network segmentation is not strictly enforced between management interfaces and user traffic.
In terms of industry classification standards, this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. It also relates to CWE-20 Improper Input Validation regarding the failure to verify data integrity before processing. From a tactical perspective within the MITRE ATT&CK framework, exploitation techniques fall under T1059 Command and Scripting Interpreter where attackers use native operating system utilities or scripts to execute malicious code. The specific vector of using UDP messages for remote execution may also relate to network service abuse patterns found in lateral movement scenarios if the attacker seeks to propagate within a segmented environment after initial compromise.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. DrayTek has released firmware updates that patch this vulnerability by implementing strict input validation and sanitization routines for all parameters passed to shell commands from the dray_apm component. Administrators should immediately apply these vendor-provided patches to bring affected VigorAP models up to a secure baseline configuration. In addition to applying software fixes, network segmentation is crucial; management interfaces of access points should be isolated on dedicated VLANs separate from general user traffic and critical server networks. Access control lists (ACLs) should restrict UDP port access used by the speed test functionality to only trusted administrative IP addresses rather than allowing broad or unrestricted access across the subnet. Regular vulnerability scanning and monitoring for anomalous outbound network connections can also help detect potential exploitation attempts early, ensuring that any unauthorized command execution is identified before it leads to persistent compromise of the infrastructure.