CVE 2008-3115
Secure Static Versioning in Sun Java JDK and JRE 6 Update 6 and earlier, and 5.0 Update 6 through 15, does not properly prevent execution of applets on older JRE releases, which might allow remote attackers to exploit vulnerabilities in these older releases.
See the 
CVE page on Mitre.org
for more details.
