WebKit, as used in Apple iTunes before 10.2 on Windows, does not properly access glyph data during layout actions for floating blocks associated with pseudo-elements, which allows man-in-the-middle attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via vectors related to iTunes Store browsing, a different vulnerability than other CVEs listed in APPLE-SA-2011-03-02-1.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.