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TI-2021-04423 Aliases CVE-2021-21323

Regression in DNS leakage from Tor windows

Priority LOW 28CWE-200Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-200.

Summary

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

Why it matters now

EPSS 0.0226 83rd percentileScored 2026-11-07
Fix Fixed brave-browser (brave): 1.20.108

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
Bravebrave-browser1.17.73 to before 1.20.1081.20.108Patch availableCNA
  • brave-browser VendorBrave Affected 1.17.73 to before 1.20.108 Fixed in 1.20.108 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:brave:brave:*:*:*:*:*:*:*:*1.17.73 – 1.20.103VulnerableBrave
  • cpe:2.3:a:brave:brave:*:*:*:*:*:*:*:* Versions 1.17.73 – 1.20.103 Vulnerable ·Brave

Remediation

  • Fix · CNA brave-browser (brave) Fixed in 1.20.108

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21323

References

Patch 3

Advisory 2

  • TI-2022-23748 Brave Browser before 1.43.88 allowed a remote attacker to cause a denial of service in… CVSS 3.1MEDIUM 6.5
  • TI-2022-23747 Brave Browser before 1.42.51 allowed a remote attacker to cause a denial of service via a… CVSS 3.1MEDIUM 6.5
  • TI-2017-05997 Brave 0.12.4 has a Status Bar Obfuscation issue in which a redirection target is shown in… CVSS 3.1MEDIUM 5.3
  • TI-2021-20894 In Brave Desktop 1.17 through 1.33 before 1.33.106, when CNAME-based adblocking and a… CVSS 3.1HIGH 7.5
  • TI-2021-05777 Information disclosure in https://github.com/brave/brave-core CVSS 3.1MEDIUM 5.9
  • TI-2022-23746 Brave Browser before 1.43.34 allowed a remote attacker to cause a denial of service via a… CVSS 3.1MEDIUM 6.5
See all 14 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences