A use after free issue exists in WebKit's handling of the removal of container elements. Visiting a maliciously crafted website may lead to an unexpected application termination or arbitrary code execution. This issue is addressed through improved memory reference tracking.
Trac: http://trac.webkit.org/changeset/55462, http://trac.webkit.org/changeset/55465
Red Hat would like to thank Drew Yao of Apple Product Security for responsibly reporting this issue. Upstream acknowledges wushi of team509, working with TippingPoint's Zero Day Initiative as the original reporter.