An issue was discovered in Mbed TLS 3.5.x before 3.6.0. When an SSL context was reset with the mbedtlssslsessionreset() API, the maximum TLS version to be negotiated was not restored to the configured one. An attacker was able to prevent an Mbed TLS server from establishing any TLS 1.3 connection, potentially resulting in a Denial of Service or forced version downgrade from TLS 1.3 to TLS 1.2.

An issue was discovered in Mbed TLS 3.6 before 3.6.1. A stack buffer overflow in mbedtlsecdsadertoraw() and mbedtlsecdsarawtoder() can occur when the bits parameter is larger than the largest supported curve. In some configurations with PSA disabled, all values of bits are affected. (This never happens in internal library calls, but can affect applications that call these functions directly.)