Vulnerability · Published Feb 23, 2021 · Assigned by GitHub_M

CVE-2021-21323Regression in DNS leakage from Tor windows

Medium 4.3

In plain English

A medium-severity information exposure in brave-browser from brave. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.3% (higher than 83% of all known vulnerabilities).

Severity (CVSS 3.1)4.3Medium

Exploit odds (30 days)2.3%top 16.9% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

Brave is an open source web browser with a focus on privacy and security. In Brave versions 1.17.73-1.20.103, the CNAME adblocking feature added in Brave 1.17.73 accidentally initiated DNS requests that bypassed the Brave Tor proxy. Users with adblocking enabled would leak DNS requests from Tor windows to their DNS provider. (DNS requests that were not initiated by CNAME adblocking would go through Tor as expected.) This is fixed in Brave version 1.20.108

Affected products (as reported)

Vendor	Product	Versions
brave	brave-browser	>= 1.17.73, < 1.20.108

Weakness: CWE-200 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

References

https://github.com/brave/brave-browser/security/advisories/GHSA-mqjf-9x5g-2rv6 x_refsource_CONFIRM
https://github.com/brave/brave-browser/issues/13527 x_refsource_MISC
https://github.com/brave/brave-core/pull/7769 x_refsource_MISC
https://github.com/brave/brave-core/commit/12fe321eaad8acc1cbd1d70b4128f687777bcf15 x_refsource_MISC
https://hackerone.com/reports/1077022 x_refsource_MISC