Integer overflow in the regular expression engine in Perl 5.8.x allows context-dependent attackers to cause a denial of service (stack consumption and application crash) by matching a crafted regular expression against a long string.
https://bugzilla.redhat.com/show_bug.cgi?id=580605
http://www.openwall.com/lists/oss-security/2010/04/14/3
http://www.openwall.com/lists/oss-security/2010/04/08/9