The bdfReadCharacters function in bitmap/bdfread.c in X.Org libXfont before 1.4.9 and 1.5.x before 1.5.1 does not properly handle character bitmaps it cannot read, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) and possibly execute arbitrary code via a crafted BDF font file.<a href=http://cwe.mitre.org/data/definitions/476.html>CWE-476: NULL Pointer Dereference</a> http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-1803
