Use After Free
HTTP applications (servers) based on Crow through 1.0+4 may allow a Use-After-Free and code execution when HTTP pipelining is used. The HTTP parser supports HTTP pipelining, but the asynchronous Connection layer is unaware of HTTP pipelining. Specifically, the Connection layer is unaware that it has begun processing a later request before it has finished processing an earlier request.
CWE-416 - Use After Free
Use-after-free (UaF) vulnerability occurs when the application is using a pointer to memory that has been freed. Any attempt to read/write to a buffer after it is de-allocated allows memory corruption, sensitive information exposure, and can potentially lead to arbitrary code execution.