In Xpdf 4.01.01, a heap-based buffer overflow could be triggered in DCTStream::decodeImage() in Stream.cc when writing to frameBuf memory. It can, for example, be triggered by sending a crafted PDF document to the pdftotext tool. It allows an attacker to use a crafted pdf file to cause Denial of Service, an information leak, or possibly unspecified other impact.
The product writes data past the end, or before the beginning, of the intended buffer.