Zero-Day Advisory

Fortinet Discovers VMWare Subdomain Takeover Vulnerability


Fortinet's FortiGuard Labs has discovered the subdomain takeover vulnerability.

The subdomain takeover vulnerability is caused by a misconfigured DNS entry. It exists because is using the Netlify Domain Controller, pointing one of its subdomains to an unregistered Netlify subdomain. As a result, it can allow attackers to hijack cookies, bypass Cross-Origin Resource Sharing (CORS), bypass Content-Security Policies (CSP), cheat the password manager applications, intercept emails, etc. by registering the subdomain.


VMware has removed the subdomain.


Fortinet reported the vulnerability to VMware on Oct 21, 2019.

VMware confirmed the vulnerability on Oct 21, 2019.

VMware patched the vulnerability on Oct 29, 2019.


This vulnerability was discovered by Zhouyuan Yang of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.