A flaw was found in the xdg-email component of xdg-utils-1.1.0-rc1 and newer. When handling mailto: URIs, xdg-email allows attachments to be discreetly added via the URI when being passed to Thunderbird. An attacker could potentially send a victim a URI that automatically attaches a sensitive file to a new email. If a victim user does not notice that an attachment was added and sends the email, this could result in sensitive information disclosure. It has been confirmed that the code behind this issue is in xdg-email and not in Thunderbird.
Upstream commit: https://gitlab.freedesktop.org/Mic92/xdg-utils/-/commit/1f199813e0eb0246f63b54e9e154970e609575af
Name: Jens Mueller (Ruhr University Bochum)
xdg-utils bug: https://gitlab.freedesktop.org/xdg/xdg-utils/-/issues/177
Created flatpak-xdg-utils tracking bugs for this issue:
Affects: fedora-31 [bug 1899773]
Affects: fedora-32 [bug 1899774]
Affects: fedora-33 [bug 1899775]
Created xdg-utils tracking bugs for this issue:
Affects: fedora-31 [bug 1899770]
Affects: fedora-32 [bug 1899771]
Affects: fedora-33 [bug 1899772]
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.
This flaw is out of support scope for Red Hat Enterprise Linux 6 and 7. Please see https://access.redhat.com/support/policy/updates/errata/ for more details.
No acceptable patch upstream, the only one there is regresses features being used. And the available mitigation explained above seems pretty natural in general. Making this WONTFIX.