CVE-2021-45884

Name: CVE-2021-45884
Creator: NVD / NIST
Published: 2021-12-27T22:15:07.847+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.68%

Last modified Jun 17, 2026

CVE-2021-45884 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. In Brave Desktop 1.17 through 1.33 before 1.33.106, when CNAME-based adblocking and a proxying extension with a SOCKS fallback are enabled, additional DNS requests are issued outside of the proxying extension using the system's DNS settings, resulting in information disclosure. NOTE: this issue exists because of an incomplete fix for CVE-2021-21323 and CVE-2021-22916.. EPSS estimates a 2.68% chance of exploitation in the next 30 days.

Description

In Brave Desktop 1.17 through 1.33 before 1.33.106, when CNAME-based adblocking and a proxying extension with a SOCKS fallback are enabled, additional DNS requests are issued outside of the proxying extension using the system's DNS settings, resulting in information disclosure. NOTE: this issue exists because of an incomplete fix for CVE-2021-21323 and CVE-2021-22916.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

2.68%

83.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-200

Affected Software

Vendor	Product	Versions
Brave	Brave	>= 1.17.1, <= 1.33.106

References

https://github.com/brave/brave-browser/issues/19070Exploit, Issue Tracking, Patch, Third Party Advisory
https://github.com/brave/brave-browser/issues/20079Issue Tracking, Release Notes, Third Party Advisory
https://github.com/brave/brave-core/pull/10742Patch, Third Party Advisory
https://hackerone.com/reports/1377864Permissions Required
https://github.com/brave/brave-browser/issues/19070Exploit, Issue Tracking, Patch, Third Party Advisory
https://github.com/brave/brave-browser/issues/20079Issue Tracking, Release Notes, Third Party Advisory
https://github.com/brave/brave-core/pull/10742Patch, Third Party Advisory
https://hackerone.com/reports/1377864Permissions Required

Timeline

Published: Dec 27, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-45884?

How severe is CVE-2021-45884?

CVE-2021-45884 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.68% probability of exploitation in the next 30 days.

How do I fix CVE-2021-45884?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-45884?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST