Termux

Part 2: How Third-Party Developers Closed the tun0 Leak in AmneziaVPN on Android

Third-party contributors to AmneziaVPN have detailed their fix for a VPN tunnel bypass affecting excluded applications on Android. The vulnerability allows any app, even those disallowed from the VPN, to bind sockets directly to the tun0 interface using SO_BINDTODEVICE and thereby discover the VPN server address. The team implemented a packet filter inside the client that queries Android via ConnectivityManager.getConnectionOwnerUid to determine packet ownership and drops traffic from unknown UIDs. The solution was integrated into both the Xray and AmneziaWG traffic paths, with the AmneziaWG hook placed inside amneziawg-go after packet parsing. Testing with leak_probe.py showed zero successful bypass attempts out of six methods when the filter was active, compared to six out of six without it. The developers submitted three pull requests and released a side-loaded test build, while noting remaining limitations such as raw sockets and tethering scenarios.