An issue was discovered in Qt before 5.15.16, 6.x before 6.2.10, and 6.3.x through 6.5.x before 6.5.3 on Windows. When using the GDI font engine, if a corrupted font is loaded via QFontDatabase::addApplicationFont{FromData], then it can cause the application to crash because of missing length checks. References: https://codereview.qt-project.org/c/qt/qtbase/+/503026