wolfSSL before 5.4.0 allows remote attackers to cause a denial of service via DTLS because a check for return-routability can be skipped.

An issue was discovered in wolfSSL before 5.5.0 (when --enable-session-ticket is used); however, only version 5.3.0 is exploitable. Man-in-the-middle attackers or a malicious server can crash TLS 1.2 clients during a handshake. If an attacker injects a large ticket (more than 256 bytes) into a NewSessionTicket message in a TLS 1.2 handshake, and the client has a non-empty session cache, the session cache frees a pointer that points to unallocated memory, causing the client to crash with a "free(): invalid pointer" message. NOTE: It is likely that this is also exploitable during TLS 1.3 handshakes between a client and a malicious server. With TLS 1.3, it is not possible to exploit this as a man-in-the-middle.