Code: is_link_trusted (NautilusFile *file,
                 gboolean      is_launcher)
 {
     GFile *location;
     gboolean res;
 
     if (!is_launcher)
     {
         return TRUE;
     }
 
    if (nautilus_file_can_execute (file))
     {
         return TRUE;
     }

    res = FALSE;

    if (nautilus_file_is_local (file))
    {
        location = nautilus_file_get_location (file);
        res = nautilus_is_in_system_dir (location);
        g_object_unref (location);
    }

    return res;
}

Vulnerability Type: Exec Code 
CWE ID: CWE-20
Summary: GNOME Nautilus before 3.23.90 allows attackers to spoof a file type by using the .desktop file extension, as demonstrated by an attack in which a .desktop file's Name field ends in .pdf but this file's Exec field launches a malicious *sh -c* command. In other words, Nautilus provides no UI indication that a file actually has the potentially unsafe .desktop extension; instead, the UI only shows the .pdf extension. One (slightly) mitigating factor is that an attack requires the .desktop file to have execute permission. The solution is to ask the user to confirm that the file is supposed to be treated as a .desktop file, and then remember the user's answer in the metadata::trusted field.
Commit Message: mime-actions: use file metadata for trusting desktop files

Currently we only trust desktop files that have the executable bit
set, and don't replace the displayed icon or the displayed name until
it's trusted, which prevents for running random programs by a malicious
desktop file.

However, the executable permission is preserved if the desktop file
comes from a compressed file.

To prevent this, add a metadata::trusted metadata to the file once the
user acknowledges the file as trusted. This adds metadata to the file,
which cannot be added unless it has access to the computer.

Also remove the SHEBANG "trusted" content we were putting inside the
desktop file, since that doesn't add more security since it can come
with the file itself.

https://bugzilla.gnome.org/show_bug.cgi?id=777991