CVE-2021-21323

MEDIUM

Brave 1.17.73-1.20.103 - DNS Request Leak via CNAME Adblocking Bypass

Title source: llm
STIX 2.1

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

References (5)

Core 5
Core References
Patch, Third Party Advisory x_refsource_misc
https://github.com/brave/brave-browser/issues/13527
Patch, Third Party Advisory x_refsource_misc
https://github.com/brave/brave-core/pull/7769
Permissions Required, Third Party Advisory x_refsource_misc
https://hackerone.com/reports/1077022

Scores

CVSS v3 4.3
EPSS 0.0195
EPSS Percentile 77.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Details

CWE
CWE-200
Status published
Products (1)
brave/brave 1.17.73 - 1.20.103
Published Feb 23, 2021
Tracked Since Feb 18, 2026