CVE 2009-1099
Integer signedness error in Java SE Development Kit (JDK) and Java Runtime Environment (JRE) 5.0 Update 17 and earlier, and 6 Update 12 and earlier, allows remote attackers to access files or execute arbitrary code via crafted glyph descriptions in a Type1 font, which bypasses a signed comparison and triggers a buffer overflow.
See the 
CVE page on Mitre.org
for more details.
