CVE-2026-71920

Multiple DrayTek VigorSwitch models contain a null pointer dereference vulnerability in the formlogout function. The vulnerability is caused by missing checks for an empty or absent Cookie header before string handling. A remote attacker can trigger this vulnerability via a crafted request to crash the service and cause a denial of service. Exploitation requires valid administrative credentials for the device's web management interface.

CVSS v3 4.9 MEDIUM

4.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/
https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-null-pointer-dereference-via-formlogout

Configurations

No configuration.

History

13 Oct 2026, 09:10

Type	Values Removed	Values Added
Summary		(es) Múltiples modelos de DrayTek VigorSwitch contienen una vulnerabilidad de desreferencia de puntero nulo en la función formlogout. La vulnerabilidad es causada por la falta de comprobaciones para un encabezado cookie vacío o ausente antes del manejo de cadenas. Un atacante remoto puede activar esta vulnerabilidad a través de una solicitud manipulada para bloquear el servicio y causar una denegación de servicio. La explotación requiere credenciales administrativas válidas para la interfaz de gestión web del dispositivo.

Information

Published : 2026-08-24 18:17

Updated : 2026-10-13 09:10

NVD link : CVE-2026-71920

Mitre link : CVE-2026-71920

CVE.ORG link : CVE-2026-71920

JSON object : View

Products Affected

No product.

CWE

CWE-476

NULL Pointer Dereference

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The vulnerability is caused by missing checks for an empty or absent Cookie header before string handling. A remote attacker can trigger this vulnerability via a crafted request to crash the service and cause a denial of service. Exploitation requires valid administrative credentials for the device's web management interface."}, {"lang": "es", "value": "M\u00faltiples modelos de DrayTek VigorSwitch contienen una vulnerabilidad de desreferencia de puntero nulo en la funci\u00f3n formlogout. La vulnerabilidad es causada por la falta de comprobaciones para un encabezado cookie vac\u00edo o ausente antes del manejo de cadenas. Un atacante remoto puede activar esta vulnerabilidad a trav\u00e9s de una solicitud manipulada para bloquear el servicio y causar una denegaci\u00f3n de servicio. La explotaci\u00f3n requiere credenciales administrativas v\u00e1lidas para la interfaz de gesti\u00f3n web del dispositivo."}], "lastModified": "2026-10-13T09:10:00.323", "sourceIdentifier": "disclosure@vulncheck.com"}