curl: NULL Pointer Dereference (DoS) in libcurl SFTP QUOTE command parsing due to missing return statement

Summary: A logic flaw in lib/vssh/libssh2.c causes a NULL pointer dereference when parsing SFTP QUOTE commands with trailing garbage. The function returnquoteerror is called to handle errors and free memory, but the return keyword is missing in several blocks e.g., lines 840, 857, 870. This allow...