Raptor RDF Syntax Library from 2.0.15 through 2.0.16 contains a heap-based buffer overflow vulnerability in raptor_new_term_from_counted_literal() caused by truncating language tag length to an unsigned char. Attackers can supply Turtle, TriG, N-Triples or N-Quads documents with language tags of 256 bytes or longer to corrupt heap memory, crash applications, and possibly execute code.