mt-daapd -- integer overflow

FrSIRT reports:

A vulnerability has been identified in mt-daapd which could be exploited
by remote attackers to cause a denial of service or compromise an
affected system. This issue is caused by a buffer overflow error in the
ws_getpostvars() function when processing a negative Content-Length:
header value, which could be exploited by remote unauthenticated
attackers to crash an affected application or execute arbitrary
code.