CVE-2026-71931
Received Received - Intake

Command Injection in DrayTek VigorSwitch

Publication date: 2026-08-24

Last updated on: 2026-08-24

Assigner: VulnCheck

Description
Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the tftp_upgrade function. The vulnerability is caused by insufficient filtering before the filename field is concatenated into a command. 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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Meta Information

Published
2026-08-24
Last Modified
2026-08-24
Generated
2026-08-24
AI Q&A
2026-08-24
EPSS Evaluated
N/A
NVD
CVE-2026-71931
EUVD
EUVD-2026-64990

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
draytek vigorswitch *
draytek vigorswitch From G2540xs (inc) to FX2120 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

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Executive Summary

This is an OS command injection vulnerability in multiple DrayTek VigorSwitch models. It exists in the tftp_upgrade function due to insufficient input validation. Attackers can inject and execute arbitrary commands with root privileges by sending crafted input to the filename field. Exploitation requires valid administrative credentials for the device's web management interface.

Detection Guidance

Detecting this vulnerability requires checking if your DrayTek VigorSwitch devices are running affected firmware versions. Log in to the web management interface and verify the model and version against DrayTek's advisory. Network scanning tools like Nmap can identify exposed VigorSwitch devices by detecting open ports (e.g., 80, 443).

Commands to check for affected models: nmap -p 80,443 <target_IP> to scan for open web interfaces. Inspect the device's firmware version in the web UI under System > Firmware.

Impact Analysis

An attacker could gain full control of the affected device, allowing them to manipulate network traffic, install malware, or use the device as a pivot point for further attacks. Since the commands execute with root privileges, the impact is severe and could compromise the entire network.

Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, violating compliance requirements under GDPR and HIPAA. Organizations may face legal penalties, reputational damage, and loss of customer trust if such incidents occur due to unpatched systems.

Mitigation Strategies

Immediately update the firmware of all affected DrayTek VigorSwitch devices to the latest patched version provided by DrayTek. Ensure administrative credentials are strong and not shared. Disable unnecessary services like TFTP if not required. Monitor network traffic for unusual activity.

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