The asn1_signature function in asn1.c in Cameron Hamilton-Rich axTLS through 2.1.5 has a Buffer Overflow that allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted certificate in the TLS certificate handshake message, because the result of get_asn1_length() is not checked for a minimum or maximum size.
https://seclists.org/bugtraq/2019/Nov/44
http://packetstormsecurity.com/files/155500/axTLS-2.1.5-Denial-Of-Service.html