QXmlStream in Qt 5.x before 5.11.3 has a double-free or corruption during parsing of a specially crafted illegal XML document.
http://lists.opensuse.org/opensuse-security-announce/2018-12/msg00066.html
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00057.html
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00071.html
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00073.html
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00090.html
https://access.redhat.com/errata/RHSA-2019:2135
https://access.redhat.com/errata/RHSA-2019:3390
https://lists.debian.org/debian-lts-announce/2019/01/msg00004.html
https://lists.debian.org/debian-lts-announce/2019/05/msg00014.html
https://lists.debian.org/debian-lts-announce/2020/09/msg00023.html