handle_messages in eXtl_tls.c in eXosip before 5.0.0 mishandles a negative value in a content-length header.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2014-1146
http://git.savannah.nongnu.org/cgit/exosip.git/commit/?id=2549e421c14aff886629b8482c14af800f411070