Matrix SSL 4.x through 4.6.0 and Rambus TLS Toolkit have a length-subtraction integer overflow for Client Hello Pre-Shared Key extension parsing in the TLS 1.3 server. An attacked device calculates an SHA-2 hash over at least 65 KB (in RAM). With a large number of crafted TLS messages, the CPU becomes heavily loaded. This occurs in tls13VerifyBinder and tls13TranscriptHashUpdate.

An issue in MatrixSSL 4.5.1-open and earlier leads to failure to securely check the SessionID field, resulting in the misuse of an all-zero MasterSecret that can decrypt secret data.

MatrixSSL 4.0.4 through 4.5.1 has an integer overflow in matrixSslDecodeTls13. A remote attacker might be able to send a crafted TLS Message to cause a buffer overflow and achieve remote code execution. This is fixed in 4.6.0.