A use after free issue exists in WebKit's handling of attribute manipulation. 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/53501, http://trac.webkit.org/changeset/53504
Red Hat would like to thank Drew Yao of Apple Product Security for responsibly reporting this issue. Upstream acknowledges Ralf Philipp Weinmann working with TippingPoint's Zero Day Initiative as the original reporter.