Why Your VPN May Not Be As Secure As It Claims

**Executive Summary:** Research from Leviathan Security demonstrates a practical technique where an attacker or compromised network device on a local (untrusted) network abuses DHCP option 121 and DHCP starvation to push more-specific routes that override VPN virtual interface routes, causing selected traffic to exit the VPN unencrypted; the report includes a PoC, impact analysis, and mitigations such as using cellular hotspots, Android devices (which ignore option 121), running VPNs in VMs (not bridged), and deep packet inspection approaches.