I used gdb to debug the problem, and found that an exception was thrown in u8_to_u32_iterator::invalid_sequence() [boost/regex/pending/unicode_iterator.hpp], which was called in parse_headers() [boost/network/protocol/http/server/impl/parsers.ipp]. The program didn't catch the exception, so it lead to crash.

An easy way to fix the bug is to catch the exception in handle_read_data(), and then return Bad Request to clients.

boost version: 1.57
cpp-netlib version: 0.11-devel