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WebRTC leak

Also called WebRTC IP leak, WebRTC leak test, ICE candidate leak, STUN leak

Definition

A WebRTC leak is when a page learns your real IP address through the browser's real-time communication feature, which gathers network addresses directly instead of through the proxy that carries the rest of your traffic.

Last updated 7 November 2026

How it works

WebRTC lets a page set up voice, video and data connections directly between browsers. To find a route, the browser gathers “candidates”: its local network addresses and, by asking a STUN server over UDP, its public address. A page can read those candidates in JavaScript with no permission prompt for a data connection.

A proxy set for web traffic usually carries TCP only. If the browser sends the STUN request straight out over UDP, the public address it learns is your real one, and the page can read it next to the proxy’s address. That is the leak. Browsers have narrowed it over the years (local addresses are now often hidden behind random .local names), but the public address is still exposed by default.

Why it matters when you run several accounts

If every profile’s proxy is undone by WebRTC revealing the same real IP, the profiles are linked by the one value that was meant to differ. It also creates a contradiction: a visitor who appears in two countries at once.

How SoftGlaze Browser handles it

WebRTC has five modes per profile: Forward (the default), Replace, Real, Disabled and Proxy UDP. When a profile has a proxy and the mode isn’t Real, Chromium is told not to send UDP outside the proxy, and the candidates a page can read are cleaned: public addresses become the proxy’s IP when it is known, otherwise they are dropped. Disabled removes the connection interface altogether. Geo auto-match, on by default, also sets the WebRTC address from the proxy’s location at launch.

Sources

  1. WebRTC APIMDN Web Docs
  2. RFC 8828: WebRTC IP Address Handling RequirementsIETF
  3. RFC 8445: Interactive Connectivity Establishment (ICE)IETF

Outside sources were checked in November 2026. Browsers, standards and vendors' pages change, so details that depend on them are as of that month.

Related terms

  • DNS leakA DNS leak is when the lookups that turn site names into IP addresses go out through your own network and resolver instead of through the proxy or VPN, revealing which sites you visit and roughly where you are.
  • Proxy serverA proxy server is a computer that forwards your requests to websites and passes the answers back, so the sites see the proxy's IP address instead of yours.
  • QUIC and HTTP/3QUIC is an encrypted transport protocol that runs over UDP instead of TCP, and HTTP/3 is the version of HTTP that runs on it; browsers use them to load sites faster where the server supports them.
  • Timezone mismatchA timezone mismatch is when the time zone a browser reports does not fit the location of the IP address it connects from, for example a browser on London time arriving from a New York address.
  • SOCKS5SOCKS5 is a proxy protocol that relays network connections of any kind between your device and a destination, with optional username and password authentication, and can pass the destination's hostname for the proxy to resolve.

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See it in SoftGlaze Browser

Separate profiles, each with its own cookies, device values and proxy, on Windows. Try the app's screens in your browser first, or start the free trial; no card needed.

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