Windows

The platform where the routing table is the battleground

Windows routes traffic through a table every local attacker can try to influence - which is what TunnelVision did with a crafted DHCP answer, pulling traffic around tunnels on affected configurations[1]. 30 providers ship Windows clients here; the ranking differentiator is not the UI but the firewall design underneath.

The legacy leaks that never die

Windows carries two decades of tunnel-hostile legacy: Teredo tunneling, 6to4, and IPv6 routes that predate every VPN client and still default to bypassing IPv4-only tunnel configs[6]. Each serious client blocks or tunnels IPv6; each Windows feature update re-enables parts of the stack. The kill-switch layer must cover both families - and the leak test checks them explicitly, because a client that handles IPv4 perfectly and forgets IPv6 is the most common Windows half-fix[4][5].

The response differential

PIA's TunnelVision response[2] and Mullvad's TunnelCrack analysis[3] are the two public benchmarks: both explain the attack class and name their mitigation layer. Compare that with providers whose response to a CVE-numbered local bypass was a support-article FAQ. The Windows kill switch that matters operates at the Windows Filtering Platform - the same layer the attacks target[4][5]. The provider comparison carries each operator's evidence class next to its Windows notes.

The client-layer attack surface, quantified

Why does the client matter more on Windows than the protocol? Because the exploit market prices it: Zerodium's bounty list names Windows VPN clients specifically[5], and the attack classes (routing manipulation, driver-level bypass) all target the client's privilege layer rather than the tunnel's cryptography. WireGuard's minimal codebase shrinks the surface; OpenVPN's TAP driver history shows the alternative. The practical takeaway: on Windows, prefer clients with published security assessments and a small attack surface over feature-rich suites with plugin ecosystems - the open-source hub ranks exactly that property.

The Windows-specific checklist

Four platform items beyond the usual: IPv6 and Teredo blocked or tunneled (legacy leaks die hard[6]); WFP-level firewall rules, not an app toggle; WireGuard as the default protocol with TCP-fallback for hostile networks; and the four-moment test from the leak test after every Windows update - feature updates reset network stacks in ways that silently re-break client configs. The account side is unchanged since the no-kyc hub: the Microsoft Store install anchors to your identity whether or not the tunnel does its job. A Developer-ID install outside the Store keeps that one anchor out of the chain, at the cost of manually checking the notarization.