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authorDavid Göransson <david.goransson@mullvad.net>2025-03-25 16:21:57 +0100
committerDavid Göransson <david.goransson@mullvad.net>2025-03-26 08:56:21 +0100
commit77e13f0a75d9a206e3166dc6df2caab0ca294b5d (patch)
tree280daa01da4eea6c5745afcacae017404c892d38 /docs
parent57c47ee9b787607952db7d1d04e7144548a15b21 (diff)
downloadmullvadvpn-77e13f0a75d9a206e3166dc6df2caab0ca294b5d.tar.xz
mullvadvpn-77e13f0a75d9a206e3166dc6df2caab0ca294b5d.zip
Update the issue of android reconfiguration leaks
Broaden the known issue of leaks on android, describing more in detail what may leak during VPN tunnel configuration change.
Diffstat (limited to 'docs')
-rw-r--r--docs/known-issues.md31
1 files changed, 20 insertions, 11 deletions
diff --git a/docs/known-issues.md b/docs/known-issues.md
index 1a43886bf5..73c8a6e2bc 100644
--- a/docs/known-issues.md
+++ b/docs/known-issues.md
@@ -102,25 +102,34 @@ is not really possible, or hard to implement on some operating systems. See the
[split tunneling documentation]: ./split-tunneling.md#dns
-### Temporary DNS leaks while tunnel is being reconfigured on Android
+### Temporary leaks while tunnel is being reconfigured on Android
-DNS lookups performed directly with the C function `getaddrinfo` can leak for a short period
-of time while an android VPN app is being re-configured (reconnecting, force-stopped etc).
-These leaks happens even when the system setting "Block connections without VPN" is
-enabled.
+Android may leak for a short period of time while a VPN tunnel is being reconfigured
+(reconnecting, force-stopped etc), sending traffic outside the tunnel that is supposed to be inside
+the tunnel. Packets sent may have the source IP of the internal tunnel interface. Some of these
+leaks can happen even when the system setting "Block connections without VPN" is enabled.
+
+The known leaks include, but may not be limited to, the following type of traffic:
+- Any traffic sent by the current VPN app (e.g API requests).
+- DNS lookups performed directly with the C function `getaddrinfo`.
+- Private DNS traffic (e.g DNS-over-TLS).
+- [OS connectivity checks](https://issuetracker.google.com/issues/250529027).
-We have not found any leaks from apps that only use Android API:s such as [DnsResolver]. The Chrome browser is an example of an app that can use getaddrinfo [directly](https://source.chromium.org/chromium/chromium/src/+/main:android_webview/browser/aw_pac_processor.cc;l=197;drc=133b2d903fa57cfda1317bc589b349cf4c284b7c).
+Multiple reports with variants of this behaviour have surfaced over the years, however the problems
+still persist. Mullvad is not aware of any mitigation to these leaks.
-Mullvad is not aware of any mitigation to this leak. It has been reported upstream to Google,
-and we wait for their response.
+- [A few packets leak to the public network at VPN reconnection](https://issuetracker.google.com/issues/37343051)
+- [Android's VPN does not provide a seamless routing transition across VPN reconfigurations.](https://issuetracker.google.com/issues/117288570)
+- [Android 10 Private DNS breaks VPN](https://issuetracker.google.com/issues/141674015)
+- [Packets leak to the public network when VPN reconnection using seamless handover](https://issuetracker.google.com/issues/172141171)
+- [VPN leaks DNS traffic outside the tunnel](https://issuetracker.google.com/issues/337961996)
#### Timeline
-* April 22, 2024 - Mullvad became aware of the leaks, via a [reddit post](https://www.reddit.com/r/mullvadvpn/comments/1c9p96y/dns_leak_with_block_connections_without_vpn_on/)
+* April 22, 2024 - Mullvad became aware that Android could leak DNS when `getaddrinfo` was being used.
* April 30, 2024 - Mullvad [report the issue](https://issuetracker.google.com/issues/337961996) upstream to Google.
* May 3, 2024 - Mullvad [blog](https://mullvad.net/blog/dns-traffic-can-leak-outside-the-vpn-tunnel-on-android) about the findings. This post contains more details.
-
-[DnsResolver]: https://developer.android.com/reference/android/net/DnsResolver
+* Mar 12, 2025 - Mullvad realize the leaks are about much more than just DNS. This document is updated accordingly.
### Broadcast traffic to the LAN bypass the VPN on Android