raptorxmlwriterstartelementcommon in raptorxmlwriter.c in Raptor RDF Syntax Library 2.0.15 miscalculates the maximum nspace declarations for the XML writer, leading to heap-based buffer overflows (sometimes seen in raptorqnameformatasxml).
A malformed input file can lead to a segfault due to an out of bounds array access in raptorxmlwriterstartelementcommon.