TLS 1.3 vulnerabilities

In TLS 1.3, the actual record type is embedded as the last non-zero byte of the decrypted payload, optionally followed by zero padding. The code which searches for the inner record type had an off-by-one bug which could be triggered by an invalid frame, leading to an underflow followed by an unconditional NULL pointer dereference, causing a kernel panic. A remote TLS 1.3 peer can send a specially crafted record to trigger a kernel panic, resulting in a Denial of Service (DoS).

If one side of the TLS connection sends multiple key update messages post-handshake in a single record, the connection can deadlock, causing uncontrolled resource consumption. This leads to denial of service. This only affects TLS 1.3.

With TLS 1.2 connections, a client can use any supported digest, including a weaker one, instead of those specified in the CertificateRequest. This may weaken the security of the connection handshake.

With TLS 1.3 pre-shared key (PSK), a malicious or faulty server could ignore the request for PFS (perfect forward secrecy) and the client would continue the connection using PSK without PFS. This occurs when a server responds to a ClientHello containing psk_dhe_ke without a key_share extension, reducing connection security.