Memory corruption via oversized black-box log messages

Buffer overflow in libqb before 2.0.8 allows attackers to corrupt memory via an oversized message sent to the black-box logger. In _blackbox_vlogger, qb_vsnprintf_serialize uses the full buffer size for the formatted message without reserving actual_size bytes for the log header. Exploitation requires a consuming application to pass attacker-controlled, overlong content into black-box logging; the documented result is memory corruption, while code execution is not established.