CoreText in Apple Mac OS X 10.7.x before 10.7.5 allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds write or read) via a crafted text glyph.
Apple Security Advisory 2012-09-19-2 - OS X Mountain Lion v10.8.2, OS X Lion v10.7.5 and Security Update 2012-004 are now available and address Apache, BIND, CoreText, Data Security, and many other vulnerabilities.