IPv6 Leak Test

IPv6 addresses are often globally unique and tied to your ISP connection. Unlike IPv4 addresses which are frequently shared through NAT, an IPv6 address can directly identify your household or device.

If your VPN leaks IPv6 traffic, websites, advertisers, and surveillance systems can correlate your real IPv6 address with your browsing activity — completely defeating the purpose of using a VPN.

As IPv6 adoption continues to grow worldwide, this type of leak is becoming increasingly common and dangerous. Always verify that your VPN handles IPv6 properly.

Almost every home connection now runs IPv4 and IPv6 side by side. Browsers prefer IPv6 when both are available, so on a dual-stack network the majority of your traffic can take the IPv6 path by default. A VPN client that only captures IPv4 routes leaves that path untouched: the tunnel comes up, the interface looks healthy, and your real address goes out on every request anyway. The failure is silent by construction — nothing in the VPN app reports an error, because as far as it is concerned the traffic it was asked to carry is being carried correctly.

Most IPv6 leak tests declare a leak whenever an IPv6 address appears at all. That produces false alarms for anyone whose VPN correctly tunnels IPv6, which modern providers increasingly do. This test compares ownership instead: it looks at the organisation and ASN behind your IPv6 address and checks them against the network carrying your IPv4 traffic. If both exit through the same provider, your VPN is handling IPv6 and there is no leak. If your IPv6 traces back to your ISP while IPv4 exits through a VPN, that is a genuine leak.

When an address cannot be attributed to either network with confidence, the result is reported as unverified rather than guessed in either direction. That state is neither a pass nor a failure — it means the evidence is insufficient, usually because the address belongs to a transit provider or to a range our data does not cover. Re-running from the same network normally resolves it; a result that stays unverified is worth raising with your VPN provider directly.