The Brave browser offers Tor support with its private mode. It means this privacy-oriented feature with this secure browser should ensure users’ online safety. However, the Brave browser leaked .onion addresses to the public DNS servers instead of keeping them limited to Tor nodes.
Brave Browser Leaked .Onion Addresses
Brave is a secure browser that also offers Tor support with its incognito or private mode.
Ideally, this support should have kept all the users’ activities private from tracking sources or the ISPs.
However, recently, some users observed that Brave browser ironically leaked all the .onion addresses looked up via the Tor mode, to the DNS servers. This indirectly means that the browser exposed this information to the ISPs.
The users shared this information in detail in a post that they later shared on Reddit as well.
Eventually, the news gained traction and more people confirmed that the glitch exists. And that Brave actually leaked the .onion addresses.
— James Kettle (@albinowax) February 19, 2021
Regarding how this would impact a user, the researcher stated,
This is especially worrisome for those of you who use Brave browser from your normal residential IP and (for whatever reason) use the Tor feature built into the browser to access Tor sites. Your ISP or DNS provider will know that a request made to a specific Tor site was made by your IP. With Brave, your ISP would know that you accessed somesketchyonionsite.onion.
Brave Rolls Out A Fix
As the matter came into Brave’s attention, they swiftly responded to the public telling them of their vigilance.
A Brave official confirmed that they already knew of this issue following a HackerOne bug report. And that they had the patch in place within the Nightly version in beta.
However, following the bug report, they upped the patch as a stable hotfix. Also, they confirmed that the glitch existed due to their adblocker.
1. this was already reported on hackerone, was promptly fixed in nightly (so upgrade to nightly if you want the fix now)
2. since it's now public we're uplifting the fix to a stable hotfix
root cause is regression from cname-based adblocking which used a separate DNS query https://t.co/dLjeu4AXtP
— yan (@bcrypt) February 19, 2021
Eventually, the team fixed this bug for all users with the release of Brave browser version 1.20.108.
Version 1.20.108 is now available (via "About Brave" within the ☰ menu). This update fixes the DNS leak regression in Tor windows, addresses a couple crashing scenarios on macOS, and more.
— Brave Software (@brave) February 20, 2021
Hence, now, all users should update their devices with the latest browser version at the earliest to prevent further sharing of their private .onion site queries.