CVE 2009-3866
The Java Web Start Installer in Sun Java SE in JDK and JRE 6 before Update 17 does not properly use security model permissions when removing installer extensions, which allows remote attackers to execute arbitrary code by modifying a certain JNLP file to have a URL field that points to an unintended trusted application, aka Bug Id 6872824.
See the 
CVE page on Mitre.org
for more details.
