A NULL pointer dereference vulnerability exists in muhammara versions prior to 6.0.5 in the LZWDecode filter when processing PDF streams with a DecodeParms dictionary missing the EarlyChange key. This causes an access violation and crashes the process, resulting in a denial of service. The issue occurs because the code dereferences a NULL pointer without checking if the EarlyChange key is present. A fix involves adding a NULL check before dereferencing. This vulnerability affects applications that use muhammara to parse untrusted PDFs and can be triggered by a crafted PDF file.