The VpMemAlloc function in bigdecimal.c in the BigDecimal class in Ruby 1.9.2-p136 and earlier, as used on Apple Mac OS X before 10.6.7 and other platforms, does not properly allocate memory, which allows context-dependent attackers to execute arbitrary code or cause a denial of service (application crash) via vectors involving creation of a large BigDecimal value within a 64-bit process, related to an "integer truncation issue."
https://bugzilla.redhat.com/show_bug.cgi?id=682332
http://www.securitytracker.com/id?1025236
http://www.redhat.com/support/errata/RHSA-2011-0910.html
http://www.redhat.com/support/errata/RHSA-2011-0909.html
http://www.redhat.com/support/errata/RHSA-2011-0908.html
http://www.mandriva.com/security/advisories?name=MDVSA-2011:098
http://www.mandriva.com/security/advisories?name=MDVSA-2011:097
http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/trunk/ext/bigdecimal/bigdecimal.c?r1=29364&r2=30993
http://support.apple.com/kb/HT4581
http://lists.apple.com/archives/security-announce/2011/Mar/msg00006.html