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 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.

Mitigation

To mitigate this flaw, either:
1. Do not use mailto links at all
2. Always double-check in the user interface that there are no unwanted attachments before sending emails; especially when the email originates from clicking a mailto link.