Out-of-bounds write via the TLS 1.3 handshake message cache in NetX Duo in Eclipse ThreadX NetX Duo 6.5.1.202602 allows a handshake message larger than the cache writes past it and on into the rest of the session control block, which holds pointers. A malicious or compromised server can make a TLS 1.3 client produce such a message before certificate authentication completes, so no server certificate is needed to reach it.