QtGui is a module for the Qt toolkit.
QtGui’s setMarkdown has a use-after-free related to QTextMarkdownImporter::insertBlock.
A remote attacker could possibly execute arbitrary code with the privileges of the process, or cause a Denial of Service condition.
There is no known workaround at this time.
All QtGui users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-qt/qtgui-5.14.2"
Note that the Qt suite is best kept in sync, so a world upgrade may be advisable to keep your system in a good state.