DrayTek VigorSwitch Web Management Interface fdftDevice username/password command injection

Summaryinfo

A vulnerability, which was classified as very critical, has been found in DrayTek VigorSwitch. This affects the function fdftDevice of the component Web Management Interface. This manipulation of the argument username/password causes command injection. The identification of this vulnerability is CVE-2026-71928. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as very critical was found in DrayTek VigorSwitch (affected version unknown). Affected by this vulnerability is the function fdftDevice of the component Web Management Interface. The manipulation of the argument username/password with an unknown input leads to a command injection vulnerability. The CWE definition for the vulnerability is CWE-77. The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Multiple DrayTek VigorSwitch models contain a command injection vulnerability in the fdftDevice function. The vulnerability is caused by insufficient filtering of the username and password fields 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.

It is possible to read the advisory at draytek.com. This vulnerability is known as CVE-2026-71928 since 08/08/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/24/2026). The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• DrayTek

Name

• VigorSwitch

License

• commercial

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion