WebKit in Apple Safari before 5.0.1 on Mac OS X 10.5 through 10.6 and Windows, and before 4.1.1 on Mac OS X 10.4; and webkitgtk before 1.2.6; accesses uninitialized memory during processing of the (1) :first-letter and (2) :first-line pseudo-elements in an SVG text element, which allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via a crafted document.