Mozilla Thunderbird is vulnerable to information disclosure. Attackers can use a crafted CSS in an RSS feed that would leak and reveal local path strings, which may contain user name.
www.securityfocus.com/bid/102258
www.securitytracker.com/id/1040123
access.redhat.com/errata/RHSA-2018:0061
access.redhat.com/security/updates/classification/#important
bugzilla.mozilla.org/show_bug.cgi?id=1411708
lists.debian.org/debian-lts-announce/2017/12/msg00026.html
www.debian.org/security/2017/dsa-4075
www.mozilla.org/en-US/security/advisories/mfsa2017-30/
www.mozilla.org/security/advisories/mfsa2017-30/