Integer Underflow (Wraparound) vulnerability in the multipart message parser of the libsoup HTTP library. The flaw is caused by an unsafe arithmetic operation in the soup_multipart_new_from_message() function. When a specially crafted multipart message is processed, the length calculation (end - 2 - split) can underflow, leading to invalid memory access and application crash. This can be exploited remotely without any authentication or user interaction, allowing attackers to disrupt the availability of applications or services using libsoup.