CVE 2009-1686
WebKit in Apple Safari before 4.0, iPhone OS 1.0 through 2.2.1, and iPhone OS for iPod touch 1.1 through 2.2.1 does not properly handle constant (aka const) declarations in a type-conversion operation during JavaScript exception handling, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted HTML document.
See the 
CVE page on Mitre.org
for more details.
