Short answer: What is a WebRTC leak? It is a browser privacy issue where WebRTC exposes IP or network candidate signals that do not match the route you expected. That may include local, public, VPN, IPv6, proxy, or browser candidate information depending on the browser, network, and VPN setup.
WebRTC leaks are not the same as DNS leaks, and they do not automatically prove that a VPN failed. They are a sign that browser-level real-time communication features need to be checked alongside the visible public IP, DNS route, IPv6 behavior, and browser fingerprinting signals.
Quick answer
- WebRTC enables real-time browser connections. It supports video calls, voice, screen sharing, and peer-to-peer data channels.
- A leak is an unexpected candidate signal. The browser may reveal local, public, VPN, IPv6, or network-route candidates outside your expectation.
- Browser behavior varies. Some browsers hide local IPs with mDNS or limit candidates; others may expose more detail in some setups.
- VPN, DNS, IPv6, and WebRTC are separate checks. One clean result does not prove the others are clean.
- Fixes should be tested. Browser settings, VPN leak protection, extensions, and firewall rules can change behavior differently.
What is a WebRTC leak?
WebRTC stands for Web Real-Time Communication. It is a browser technology for low-latency audio, video, screen sharing, and data connections. MDN's WebRTC API documentation and the W3C WebRTC specification describe how browsers expose WebRTC features to web applications.
A WebRTC leak happens when the browser exposes network candidates that reveal more IP-related information than the user expected. In older or less protected setups, that could include local private IP addresses, public ISP addresses, IPv6 addresses, or VPN-related candidates. In newer browser setups, local addresses may be hidden or replaced with mDNS hostnames, but testing is still useful.
The key point for users asking what is a WebRTC leak is expectation. If you expect websites to see only a VPN exit route, but WebRTC candidates reveal another route or local signal, the setup deserves review.
How WebRTC finds network candidates
WebRTC uses connection negotiation so browsers can find a workable path between peers. Interactive Connectivity Establishment, described in RFC 8445, helps choose candidate paths. STUN, described in RFC 8489, can help a browser discover network-facing address information.
That candidate discovery is useful for calls and real-time apps. It can also surprise privacy-conscious users because the browser may expose network candidates that differ from the page's visible public IP. Those candidates can include host, server-reflexive, relay, IPv4, IPv6, VPN, or proxy-related signals depending on the setup.
This does not mean every site normally sees every private address. Browser privacy changes, mDNS masking, permission models, enterprise policy, VPN design, and network routing all affect the result. That is why a browser-based WebRTC leak test should be interpreted carefully.
What WebRTC can reveal and what it cannot prove
WebRTC results can show candidate types, IP-like values, local network hints, IPv6 behavior, or whether the browser sees routes that differ from the expected VPN or proxy path. That can be useful for diagnosing a privacy mismatch.
WebRTC results do not reveal passwords, full browsing history, message contents, account names, payment details, or everything about your device. They also do not prove who personally used a browser. Like IP address data, WebRTC signals become more meaningful when combined with account logins, cookies, browser fingerprints, timestamps, device signals, and provider records.
For privacy, the risk is usually correlation. A WebRTC candidate that differs from the visible page IP can give a website or script one more signal to compare with DNS, IPv6, account, or fingerprinting information.
Common causes of WebRTC leak results
- Browser WebRTC behavior: each browser handles candidates, local addresses, and mDNS masking differently.
- VPN app design: a VPN may route normal browser traffic while WebRTC discovers candidates through a different network interface.
- IPv6 mismatch: IPv6 may be visible or routed differently from IPv4 if the VPN does not support it or block it consistently. RFC 8200 describes IPv6 itself.
- Proxy-only setup: a browser proxy may change HTTP traffic while WebRTC uses direct networking behavior.
- Split tunneling: some apps, browsers, profiles, or network interfaces may bypass the VPN.
- Extensions or policies: privacy extensions, browser flags, enterprise policies, or managed profiles can alter WebRTC behavior.
How to test for a WebRTC leak: 7 checks
- Open What Is My IP and record the visible public IP without changing settings.
- Connect the VPN, proxy, browser profile, or privacy route you want to verify.
- Run WebRTC Leak Test and review candidate IPs, candidate types, and local or IPv6 signals.
- Compare WebRTC results with the visible public IP and expected VPN or proxy route.
- Run DNS Leak Test because resolver paths are separate from WebRTC candidates. DNS over HTTPS, standardized in RFC 8484, can also change DNS behavior.
- Run IPv6 Leak Test because IPv6 may reveal a different route.
- Repeat after browser updates, VPN reconnects, server changes, extension changes, or Wi-Fi/cellular switches.
Only test browsers, devices, and networks you own or are authorized to manage. These checks are browser-session diagnostics, not permission to investigate other networks.
How to interpret WebRTC leak test results
| Result | Usually means | What to check next |
|---|---|---|
| Only VPN or expected route appears | WebRTC candidates match the route you intended | Still check DNS, IPv6, and browser fingerprinting |
| Local private address or mDNS name appears | Browser is exposing or masking local candidate information | Check browser privacy settings and whether local exposure matters for your threat model |
| ISP public IP appears while VPN is active | Possible route mismatch or VPN leak protection gap | Enable VPN leak protection, reconnect, and retest |
| IPv6 candidate appears unexpectedly | IPv6 may not follow the expected VPN or proxy route | Check VPN IPv6 support or documented IPv6 blocking behavior |
| Different browsers show different results | Browser-specific WebRTC, extension, policy, or profile behavior | Test the browser you actually use for sensitive activity |
| No candidates appear | WebRTC may be blocked, limited, or unavailable in that browser/session | Confirm whether calls or real-time apps still work if needed |
WebRTC leak vs DNS leak vs VPN leak
| Check | What it inspects | Common mismatch | Best next step |
|---|---|---|---|
| WebRTC leak | Browser network candidates | Candidate reveals unexpected local, public, VPN, proxy, or IPv6 signal | Adjust browser, VPN, WebRTC, or firewall behavior |
| DNS leak | Resolver path and domain lookup route | DNS goes to ISP, router, or browser DoH provider instead of expected DNS | Align VPN DNS, browser DNS, system DNS, and router DNS |
| VPN leak | Combined IP, DNS, WebRTC, IPv6, and browser signals | One signal follows a different route from the VPN expectation | Test each layer separately, then fix the route mismatch |
These checks overlap, but they are not interchangeable. A clean DNS result does not prove WebRTC is clean. A clean WebRTC result does not prove DNS or IPv6 is clean.
How to reduce WebRTC leak risk
- Use browser privacy settings carefully. Some browsers let you limit or disable WebRTC exposure, but settings differ by browser and version.
- Use a VPN with leak protection. Good VPN behavior should handle browser traffic, DNS, IPv6, reconnects, and route changes consistently.
- Review proxy-only setups. A proxy can change web traffic while WebRTC discovers candidates outside that proxy route.
- Check IPv6 deliberately. Prefer correct VPN IPv6 support, or use provider-documented IPv6 handling where needed.
- Be cautious with extensions. Extensions can help, but they add trust and maintenance questions. Test after installing or updating them.
- Retest after changes. Browser updates, VPN updates, network changes, and extension changes can alter WebRTC behavior.
Disabling WebRTC entirely can break video calls, voice calls, screen sharing, and real-time collaboration tools. For many users, the better first step is to test, adjust the browser or VPN setting, and retest.
When WebRTC leaks matter most
- VPN or proxy use: candidates that differ from the expected route can reduce confidence in the setup.
- Public Wi-Fi: local network and browser signals may reveal more context than expected.
- Travel: changing networks, VPN exits, and IPv6 behavior can make results inconsistent.
- Work or school devices: managed policies may control WebRTC, VPN, and DNS behavior.
- Sensitive accounts: account providers may evaluate IP, region, device, browser, and behavior signals together.
- Browser fingerprinting review: WebRTC candidates can be one signal among many browser attributes.
How to troubleshoot confusing WebRTC results
WebRTC test results can look confusing because browsers show candidate information, not a simple pass/fail privacy verdict. Start by separating the visible page IP, WebRTC candidates, DNS resolvers, IPv6 route, and browser fingerprinting signals. Each layer can be correct or mismatched independently.
- If a local candidate appears: check whether it is a private address, mDNS hostname, or another masked local signal, then decide whether local-network exposure matters for your use case.
- If the ISP public IP appears: reconnect the VPN, switch servers, enable leak protection, and test again in the same browser profile.
- If only one browser leaks: compare browser WebRTC settings, extensions, managed policies, and profile-specific privacy settings.
- If IPv6 differs from IPv4: verify whether the VPN supports IPv6, blocks IPv6, or routes it differently from IPv4.
- If calls stop working after a fix: the setting may have blocked WebRTC too aggressively; choose a more limited privacy setting if real-time calls are required.
Document the browser, operating system, VPN state, server location, visible public IP, and WebRTC candidate result when troubleshooting. That record makes it easier to see whether a change actually fixed the mismatch or simply changed which signal appeared.
What not to do
- Do not assume every WebRTC result is a severe leak. Candidate types and browser behavior need context.
- Do not treat a VPN as identity removal. A VPN changes network routing and shifts trust; it does not remove account or browser signals.
- Do not treat one clean test as full privacy proof. It is a snapshot for this browser, network, and moment.
- Do not disable features blindly. WebRTC is used for calls and collaboration, so understand the trade-off before blocking it.
- Do not ignore DNS, IPv6, and fingerprinting. WebRTC is only one layer of browser privacy review.
What to do next
If WebRTC results match your expected route, keep the setup simple and retest after major browser, VPN, extension, or network changes. If results show unexpected candidates, decide whether the issue is browser behavior, VPN routing, IPv6 handling, proxy setup, or local network exposure.
The practical answer to what is a WebRTC leak is this: it is an unexpected browser candidate signal. Fix it by aligning browser, VPN, IPv6, DNS, and firewall behavior with the route you actually intend, then verify again.
Frequently asked questions
What is a WebRTC leak?
A WebRTC leak happens when browser WebRTC network candidates reveal IP or network signals that do not match the route you expected, such as local, VPN, IPv6, or public candidate information.
Does a WebRTC leak always reveal my real IP address?
No. Browser behavior varies. Some browsers hide local IPs with mDNS or show limited candidates, while some setups may still expose public, local, VPN, IPv6, or proxy-related signals.
How do I test for a WebRTC leak?
Check your visible public IP, connect your VPN or proxy, run a WebRTC leak test, and compare the candidate IPs with the route you expected. Also check DNS and IPv6.
Is a WebRTC leak the same as a DNS leak?
No. WebRTC leaks involve browser network candidates. DNS leaks involve resolver paths and domain lookups. Both can matter, but they are different signals.
Should I disable WebRTC completely?
Only if you do not need WebRTC features and your browser supports that safely. Many users should first test, adjust browser privacy settings, and use VPN leak protection where available.
Sources and methodology
MyIPScan tools and examples show observable browser and network signals. IP and geolocation results can be approximate, and VPN, DNS, WebRTC, IPv6, ASN, reputation, and browser checks are snapshots. A single result does not prove anonymity or every security condition. See the MyIPScan methodology and editorial policy.
This FAQ was updated using MyIPScan editorial guardrails: careful WebRTC privacy wording, no VPN anonymity guarantees, no one-test privacy proof, no unsafe bypass advice, and clear distinction between WebRTC, DNS, VPN routing, IPv6, browser fingerprinting, and account tracking.