CVE-2026-71917 in VigorSwitch FX2120
Summary
by MITRE • 08/24/2026
Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the pingtrace function. The vulnerability is caused by insufficient validation of the host field before command execution. A remote attacker can trigger this vulnerability via crafted input to execute arbitrary commands with root privileges. Exploitation requires valid administrative credentials for the device's web management interface.
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Analysis
by VulDB Data Team • 08/24/2026
The DrayTek VigorSwitch series, a line of managed network switches widely deployed in enterprise and small-to-medium business environments, contains a critical command injection vulnerability within its pingtrace functionality. This flaw stems from insufficient validation and sanitization of user-supplied input specifically targeting the host field used for diagnostic operations. The underlying technical mechanism involves the device's web management interface passing this unsanitized parameter directly to an operating system shell or internal utility without adequate filtering of special characters such as semicolons, ampersands, or pipe symbols. This lack of strict input validation allows a malicious actor to inject arbitrary command-line arguments that are subsequently executed by the underlying firmware process with elevated privileges.
From a technical perspective, this vulnerability is classified under CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The severity of this issue is significantly amplified because it resides within a network-facing management interface rather than a local application feature. While the exploitation requires valid administrative credentials for the device's web management interface, which acts as a partial control mechanism, the presence of such credentials does not mitigate the risk entirely. Attackers who have obtained or guessed these credentials can leverage this flaw to achieve complete system compromise. The ability to execute commands with root privileges means that an attacker gains full control over the switch, allowing them to modify configurations, exfiltrate sensitive network traffic data, install persistent backdoors, or use the compromised device as a pivot point for further lateral movement within the internal network infrastructure.
The operational impact of this vulnerability extends beyond the immediate compromise of the affected hardware. In many organizational architectures, managed switches serve as critical nodes in the network topology, facilitating communication between various subnets and segments. A successful exploitation could lead to significant disruption of business operations by altering routing tables or VLAN configurations. Furthermore, an attacker with root access can potentially extract cryptographic keys, SNMP community strings, or other credentials stored on the device, thereby compromising the security posture of the entire connected network segment. This aligns with ATT&CK technique T1053 Scheduled Task/Job which may be used to maintain persistence, and T1046 Network Service Discovery if the attacker uses the compromised switch to scan adjacent networks for additional targets.
Mitigation strategies must prioritize immediate remediation through vendor-provided firmware updates that address this input validation flaw. Organizations should verify their inventory of DrayTek VigorSwitch models against known vulnerable versions listed in official security advisories and apply patches promptly. In scenarios where patching is not immediately feasible, network segmentation policies should be enforced to restrict access to the management interfaces of these switches exclusively from trusted administrative workstations or jump hosts using strict firewall rules. Additionally, implementing multi-factor authentication for administrative accounts can reduce the likelihood of credential compromise, although it does not eliminate the risk if credentials are already stolen. Regular vulnerability scanning and continuous monitoring of network traffic for anomalous commands directed at switch management interfaces are also recommended to detect potential exploitation attempts early in the kill chain.