The UIProcess subsystem in WebKit, as used in WebKitGTK through 2.23.90 and WebKitGTK+ through 2.22.6 and other products, does not prevent the script dialog size from exceeding the web view size, which allows remote attackers to cause a denial of service (Buffer Overflow) or possibly have unspecified other impact, related to UIProcess/API/gtk/WebKitScriptDialogGtk.cpp, UIProcess/API/gtk/WebKitScriptDialogImpl.cpp, and UIProcess/API/gtk/WebKitWebViewGtk.cpp, as demonstrated by GNOME Web (aka Epiphany).
lists.opensuse.org/opensuse-security-announce/2019-04/msg00058.html
lists.opensuse.org/opensuse-security-announce/2019-05/msg00005.html
bugs.webkit.org/show_bug.cgi?id=184875
github.com/WebKit/webkit/commit/6f9b511a115311b13c06eb58038ddc2c78da5531
trac.webkit.org/changeset/241515/webkit
usn.ubuntu.com/3948-1/
www.exploit-db.com/exploits/46465/
www.inputzero.io/2019/02/fuzzing-webkit.html